Document:

Exhibit 10.50

                          REGISTRATION RIGHTS AGREEMENT

         This  Registration  Rights Agreement is made and entered into as of the
31st day of July,  2000,  by and  among  MEDTOX  Scientific,  Inc.,  a  Delaware
corporation (the "Company"),  the Investors listed on Schedule A attached hereto
(individually,  an "Investor" and collectively,  the  "Investors"),  and Miller,
Johnson & Kuehn, Inc. ("MJK").

                                    RECITALS

     A. The  Investors  and the Company have  entered  into that  certain  Stock
Purchase Agreement, dated July 31, 2000 (the "Purchase Agreement").

     B. MJK has been retained to act as the  exclusive  agent for the Company in
connection with the offering of the Units.

         C. It is a condition to the  transactions  contemplated in the Purchase
Agreement that the Company  provide the  registration  and other rights provided
herein and the parties hereto desire to provide for such rights on the terms and
conditions contained herein.

         NOW,  THEREFORE,   in  consideration  of  the  premises  and  covenants
contained herein, the parties hereto agree as follows:

1. Defined Terms.  Unless  otherwise  noted,  all capitalized  terms used herein
shall have the meanings  afforded them in the Stock  Purchase  Agreement and the
Exhibits attached thereto.

2. Required  Registration.  Within 30 days of the Closing (the "File Date"), the
Company shall file a Registration Statement under the Securities Act of 1933, as
amended (the  "Securities  Act"),  on Form S-3 with the  Securities and Exchange
Commission  (the  "Commission")  covering  the resale of the (i) Shares and (ii)
shares of Common Stock  issuable  upon  exercise of the  Warrants  issued by the
Company  to the  Investors  and  MJK  on  the  date  hereof  (collectively,  the
"Registrable Stock"); provided,  however, that the Company will not be obligated
to file such a registration under the Securities Act:

(a) if Form S-3 or a  successor  form  thereto is not  available  to it for such
registration,  provided  that the Company has used good faith  efforts to remain
qualified to use Form S-3; or

(b) if the Company furnishes to the holders of the Registrable Stock (as defined
below) a  certificate  signed  by the Chief  Executive  Officer  of the  Company
stating that in the good faith judgment of the Company's Board of Directors, (i)
the  offering  would  interfere  in any  material  respect  with any  financing,
acquisition,  corporate  reorganization  or  other  material  transaction  under
consideration  by the Company or (ii) there is some other  material  development
relating to the condition  (financial or other) of the Company that has not been
disclosed  to the  general  public and as to which it is in the  Company's  best
interests not to disclose such  development;  provided that the aggregate period
of delay under this paragraph may not extend,  in any twelve-month  period,  for

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more than 120 days  unless the holders of a majority  of the  Registrable  Stock
consent in writing to a longer delay of up to an additional 60 days.

3. Registration - General Provisions. In connection with the registration of the
Registrable Stock under the Securities Act, the Company will:

(a)  subject  to  Section  2 above,  prepare  and file  with  the  Commission  a
registration  statement with respect to the Registrable Stock, within 30 days of
the Closing date of the Purchase Agreement,  and use its commercially reasonable
efforts to cause such  registration  statement  to be declared  effective by the
Commission  subject to Section 4 below, use its commercially  reasonable efforts
keep any  such  Registration  Statement  continuously  effective,  supplemented,
amended and current until such time as may be reasonably necessary to effect the
sale of such securities, but not to exceed the earlier of the date on which: (i)
all  Registrable  Stock has been sold,  or (ii) three years after the date it is
declared effective by the Commission;

(b)      subject to Section 4 below,  prepare and file with the Commission  such
         amendments  to  such  Registration  Statement  and  supplements  to the
         prospectus   contained  therein  as  may  be  necessary  to  keep  such
         Registration  Statement  effective  for the period  required by Section
         3(a) above;

(c)      provide one counsel, selected by and acting on behalf of the Investors,
         with reasonable  opportunities  to review and comment on, and otherwise
         participate in, the preparation of such Registration Statement;

(d)      furnish to the Investors and MJK participating in such registration and
         to the  underwriters of the securities being  registered,  if any, such
         reasonable number of copies of the Registration Statement,  preliminary
         prospectus,  final prospectus and such other documents as the Investors
         and  underwriters  may  reasonably  request in order to facilitate  the
         public offering of such securities;

(e) use its diligent,  good faith efforts to register or qualify the  securities
covered by such  Registration  Statement under such state securities or blue sky
laws of such jurisdictions as the Investors may reasonably request,  except that
the Company  shall not for any purpose be required to execute a general  consent
to service of process (which shall not include a "Uniform  Consent to Service of
Process" or other  similar  consent to service of process  which relates only to
actions  or  proceedings  arising  out of or in  connection  with  the  sale  of
securities,  or out of a violation  of the laws of the  jurisdiction  requesting
such  consent)  or to qualify to do  business  as a foreign  corporation  in any
jurisdiction wherein it is not so qualified;

(f)      notify the Investors and MJK,  promptly  after it shall receive  notice
         thereof, of the time when such Registration Statement has been declared
         effective by the Commission or a supplement to any prospectus forming a
         part of such Registration Statement has been filed with the Commission;
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          (g)  notify  the  Investors  and MJK  promptly  of any  request by the
     Commission for the amending or supplementing of such Registration Statement
     or prospectus or for additional information;

(h)      prepare and file with the Commission,  promptly upon the request of the
         Investors, any amendments or supplements to such Registration Statement
         or  prospectus  which,  in the opinion of counsel for the Investors and
         MJK (and  concurred in by counsel for the Company),  is required  under
         the Securities Act or the rules and regulations  promulgated thereunder
         in connection with the  distribution  of the  Registrable  Stock by the
         Investors;

(i)      subject  to  Section  4  below,  prepare  and  promptly  file  with the
         Commission  and  promptly  notify the  Investors  of the filing of such
         amendment or supplement to such Registration Statement or prospectus as
         may be necessary to correct any statements or omissions if, at the time
         when a  prospectus  relating  to  such  securities  is  required  to be
         delivered  under the  Securities  Act, any event shall have occurred as
         the result of which any such prospectus or any other prospectus as then
         in effect would include an untrue  statement of a material fact or omit
         to state any material fact necessary to make the statements therein, in
         the light of the circumstances in which they were made, not misleading;

(j)      advise the Investors and MJK, and the Investors' and MJK's counsel,  if
         any,  promptly  after it  shall  receive  notice  or  obtain  knowledge
         thereof, of the issuance of any stop order by the Commission suspending
         the effectiveness of such  Registration  Statement or the initiation or
         threatening  of any  proceeding  for that  purpose and promptly use its
         commercially  reasonable  efforts to prevent  the  issuance of any stop
         order or to obtain its withdrawal if such stop order should be issued;

(k)      not file any amendment or supplement to such Registration  Statement or
         prospectus to which the Investors shall have reasonably objected on the
         grounds  that  such  amendment  or  supplement  does not  comply in all
         material  respects with the  requirements  of the Securities Act or the
         rules  and  regulations  promulgated  thereunder,   after  having  been
         furnished  with a copy thereof at least five business days prior to the
         filing  thereof,  unless in the  opinion of counsel for the Company the
         filing of such  amendment  or  supplement  is  reasonably  necessary to
         protect the Company from any material  liabilities under any applicable
         federal or state law and such filing will not violate  applicable  law;
         and

(l) at the request of the Investors and/or MJK, furnish on the effective date of
the Registration  Statement and, if such  registration  includes an underwritten
public offering, at the closing provided for in the underwriting agreement:  (i)
opinions,  dated such respective dates, of the counsel  representing the Company
for the purposes of such  registration,  addressed to the underwriters,  if any,
and to the  Investors  making  such  request,  covering  such  matters  as  such
underwriters or Investors may reasonably request,  and (ii) letters,  dated such
respective  dates,  from the  independent  certified  public  accountants of the
Company, addressed to the underwriters,  if any, and to the Investors,  covering
such matters as such underwriters or Investors may reasonably  request, in which

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letter such  accountants  shall state  (without  limiting the  generality of the
foregoing) that they are independent  certified  public  accountants  within the
meaning of the  Securities Act and that in the opinion of such  accountants  the
financial  statements and other  financial  data of the Company  included in the
Registration  Statement or the prospectus or any amendment or supplement thereto
comply in all material respects with the applicable  accounting  requirements of
the Securities Act.

4. Suspension of Resales.  The holders of the Registrable Stock acknowledge that
there may  occasionally  be times when the Company  must  suspend the use of the
prospectus forming a part of the Registration  Statement, in the event that Form
S-3 becomes unavailable to the Company, if the offering of the Registrable Stock
would interfere with certain material corporate  transactions or if there exists
certain material non-public information concerning the Company. Accordingly, the
Company may suspend sales pursuant to such  Registration  Statement:  (a) if the
holders of the  Registrable  Stock are  notified in writing by the Company  that
Form S-3 is not available  for the sale of securities by such holders,  for such
period of  unavailability;  and (b) for a period of up to 120 days  (unless  the
holders of at least a majority of the Registrable  Stock consent in writing to a
longer  delay of up to an  additional  60 days) if the Company  furnishes to the
holders of the  Registrable  Stock a certificate  signed by the Chief  Executive
Officer of the Company  stating that in the good faith judgment of the Company's
Board of Directors,  (i) the offering  would  interfere in any material  respect
with any  financing,  acquisition,  corporate  reorganization  or other material
transaction  under  consideration  by the  Company  or (ii)  there is some other
material  development  relating  to the  condition  (financial  or other) of the
Company that has not been  disclosed to the general public and as to which it is
in the Company's best interests not to disclose such development;  provided that
the aggregate period of delay under this subparagraph (b) may not extend, in any
twelve-month  period, for more than 120 days unless the holders of a majority of
the  Registrable  Stock  consent  in  writing  to a  longer  delay  of  up to an
additional 60 days. The Company will notify the holders of Registrable  Stock in
any of such events (in each case, a "Black Out Notice"). Each such holder agrees
that upon its  receipt  of a Black Out  Notice  such  holder  shall  immediately
discontinue  the sale of any  Registrable  Stock  pursuant  to the  Registration
Statement until such holder has received  copies of the  supplemented or amended
prospectus  referred  to in  Section  3(i) or until  such  holder is  advised in
writing that the use of the prospectus may be resumed,  and has received  copies
of any additional or supplemental  filings that are incorporated by reference in
the prospectus.  In addition,  the holder agrees that it will either (x) destroy
any  prospectuses,  other than  permanent  file  copies,  then in such  holder's
possession  which have been  replaced by the Company  with more  recently  dated
prospectuses or (y) deliver to the Company all copies, other than permanent file
copies,  then  in such  holder's  possession  of the  prospectus  covering  such
Registrable  Stock  that was  current  at the time of  receipt  of the Black Out
Notice.  The  period  during  which the  Company is  required  to  continue  the
effectiveness of a registration  statement under Section 3(a) will be tolled for
all periods of time during which resales are suspended under this Section 4.

5. Provision by Investors of Certain Information in Connection with Registration
Statement.  No Investor or MJK may include any of its  Registrable  Stock in the
Registration Statement pursuant to this Agreement unless and until such Investor
and MJK  furnishes to the Company in writing,  within 20 days after receipt of a
request  therefor,  the  information  specified in Item 507 or 508 of Regulation
S-K,  as  applicable,  of the  Securities  Act for use in  connection  with  the

<PAGE>

Registration Statement or prospectus or preliminary prospectus included therein.
Each selling Investor and MJK agrees to promptly furnish additional  information
required to be disclosed in order to make the information  previously  furnished
to the Company by such Investor and MJK not materially misleading.

6.  Registration  Expense.  The Company shall pay all Registration  Expenses (as
defined below) in connection with the inclusion of the Registrable  Stock in any
Registration  Statement, or application to register or qualify such shares under
state securities laws, filed by the Company  hereunder,  other than as set forth
herein. For purposes of this Agreement,  the term "Registration  Expenses" means
the filing fees payable to the  Commission,  any state agency and the NASD;  the
fees and  expenses of the  Company's  legal  counsel and  independent  certified
public  accountants  in  connection  with  the  preparation  and  filing  of the
Registration  Statement (and all amendments  and  supplements  thereto) with the
Commission;  and all  expenses  relating  to the  printing  of the  Registration
Statement,  prospectuses and various agreements  executed in connection with the
Registration  Statement.  The  Company  will pay the fees and  expenses,  not to
exceed  $3,000,  of one counsel  selected by MJK to represent  the  Investors in
connection with preparation of the Registration  Statement.  Notwithstanding the
foregoing,  the  Investors  will pay the fees and  expenses  of any other  legal
counsel the Investors may engage, as well as the Investors'  proportionate share
of any custodian  fees or  commission  or discounts  which may be payable to any
underwriter.

7. Penalty  Payments.  In the event that the Company is  determined  not to have
exercised its commercially  reasonable efforts to file a Registration  Statement
relating  to the  Registrable  Stock with the  Commission  on or before the File
Date,  then,  the Company shall pay the Investors and MJK the following  amounts
("Penalty  Payments"):  (i) 1% of the purchase price of the Stock (the "Purchase
Price") paid by the  Investors  to the Company if (A) the Company is  determined
not  to  have  exercised  its  commercially   reasonable  efforts  to  file  the
Registration  Statement with the Commission by the File Date, (ii) an additional
1% of the Purchase  Price if the Company is determined not to have exercised its
commercially  reasonable efforts to cause the Registration Statement to be filed
with the Commission within 150 days of the Closing date, and (iii) an additional
3% of the Purchase Price for each 30-day period  thereafter in which the Company
is determined not to have exercised its commercially reasonable efforts to cause
the  Registration  Statement not to be filed with the Commission.  Penalties for
failure to file and/or to obtain effectiveness shall be cumulative.  The Company
shall  be  liable  to the  Investor  for a full  30-day  period,  determined  in
accordance with the above schedule, regardless of by how many days it misses one
of the  targeted  filing or effective  dates set forth  above.  All such Penalty
Payments  shall be  immediately  payable by the Company to the Investors and MJK
(on a pro rata basis  based on the number of shares of Stock  purchased  by each
under the Stock Purchase  Agreement) via wire transfer of immediately  available
funds  in the  event  that it is  determined  that the  Company  did not use its
commercially  reasonable efforts as set forth above. The Company shall be deemed
not to  have  used  its  commercially  reasonable  efforts  if the  Registration
Statement is not filed within 150 days of the Closing.

8. Indemnification. With respect to the registration of the resale of the shares
of Registrable Stock:

<PAGE>

(a) to the fullest extent  permitted by law, the Company will indemnify and hold
harmless each Investor,  MJK, the trustees,  partners,  officers,  directors and
agents of each Investor, MJK, any underwriter (as defined in the Securities Act)
for such Investor,  MJK and each person, if any, who controls such Investor, MJK
or  underwriter  within the  meaning  of the  Securities  Act or the  Securities
Exchange  Act of 1934,  as amended  (the  "Exchange  Act"),  against any losses,
claims,  damages,  or  liabilities  (joint or  several) to which they may become
subject  under the  Securities  Act, the Exchange Act or other  federal or state
law,  insofar as such  losses,  claims,  damages or  liabilities  (or actions in
respect thereof) arise out of or are based upon any of the following statements,
omissions or violations  (collectively  a "Violation")  by the Company:  (i) any
untrue statement or alleged untrue statement of a material fact contained in the
Registration Statement, including any preliminary prospectus or final prospectus
contained therein or any amendments or supplements thereto, (ii) the omission or
alleged omission to state therein a material fact required to be stated therein,
or  necessary  to make the  statements  therein  not  misleading,  or (iii)  any
violation  or alleged  violation  by the  Company  of the  Securities  Act,  the
Exchange Act, any state  securities  law or any rule or  regulation  promulgated
under the  Securities  Act,  the  Exchange  Act or any state  securities  law in
connection  with the offering  covered by the  Registration  Statement;  and the
Company will reimburse each such Investor,  trustee, partner, officer, director,
agent,  underwriter  or  controlling  person  for any  legal or  other  expenses
reasonably  incurred by them in connection with  investigating  or defending any
such loss,  claim,  damage,  liability or action;  provided,  however,  that the
indemnity  agreement contained in this Section 8 shall not apply to amounts paid
in  settlement  of any such loss,  claim,  damage,  liability  or action if such
settlement is effected  without the consent of the Company  (which consent shall
not be unreasonably withheld),  nor shall the Company be liable in any such case
for any such loss,  claim,  damage,  liability  or action to the extent  that it
arises out of or is based upon a Violation  which occurs in reliance upon and in
conformity  with  written  information  furnished  to it  expressly  for  use in
connection with such  registration by an Investor,  trustee,  partner,  officer,
director, agent, underwriter or controlling person of an Investor.

(b) to the extent  permitted by law,  each  Investor and MJK will  indemnify and
hold harmless the Company,  each of its  directors,  each of its officers,  each
person,  if any, who controls the Company  within the meaning of the  Securities
Act,  any  underwriter  and any  other  Investor  selling  securities  under the
Registration  Statement  or any of such other  Investor's,  trustees,  partners,
directors  or officers or any person who  controls  such  Investor,  against any
losses,  claims,  damages or liabilities (joint or several) to which the Company
or any such director,  officer,  controlling  person,  underwriter or other such
Investor, or trustee, partner,  director,  officer or controlling person of such
other Investor may become subject under the Securities  Act, the Exchange Act or
other  federal  or  state  law,  insofar  as such  losses,  claims,  damages  or
liabilities  (or actions in respect  thereto) arise out of or are based upon any
Violation,  in each  case to the  extent  (and  only to the  extent)  that  such
Violation  occurs in reliance  upon and in conformity  with written  information
furnished by such Investor and stated to be  specifically  for use in connection
with such registration; and each such Investor will reimburse any legal or other
expenses  reasonably  incurred  by the  Company or any such  director,  officer,
controlling person, underwriter or other Investor, or trustee, partner, officer,

<PAGE>

director  or  controlling  person of such  other  Investor  in  connection  with
investigating or defending any such loss, claim, damage,  liability or action if
it is judicially determined that there was such a Violation;  provided, however,
that the  indemnity  agreement  contained  in this  Section 8 shall not apply to
amounts paid in settlement of any such loss, claim, damage,  liability or action
if such  settlement  is effected  without the consent of the  Investor  and MJK,
which consent shall not be unreasonably  withheld;  provided further, that in no
event shall any  indemnity  under this Section 8 exceed the gross  proceeds from
the offering received by such Investor or MJK unless the Violation is the result
of fraud on the part of such Investor or MJK.

(c) promptly after receipt by an indemnified  party under this Section of notice
of the  commencement of any action  (including any  governmental  action),  such
indemnified party shall, if a claim in respect thereof is to be made against any
indemnifying  party  under this  Section,  deliver to the  indemnifying  party a
written notice of the commencement thereof and the indemnifying party shall have
the right to  participate  in,  and,  to the  extent the  indemnifying  party so
desires,  jointly with any other indemnifying party similarly noticed, to assume
the defense thereof with counsel mutually satisfactory to the parties; provided,
however,  that an  indemnified  party  shall  have the right to  retain  its own
counsel,  with the fees and expenses to be paid by the  indemnifying  party; and
provided  further,  that if  there  is more  than  one  indemnified  party,  the
indemnifying  party  shall pay for the fees and  expenses of one counsel for any
and all  indemnified  parties to be  mutually  agreed  upon by such  indemnified
parties,  unless  representation of an indemnified party by the counsel retained
by the  other  indemnified  parties  would be  inappropriate  due to  actual  or
potential differing interests between such indemnified  parties.  The failure to
deliver written notice to the indemnifying party within a reasonable time of the
commencement  of any such action,  if materially  prejudicial  to its ability to
defend such action,  shall relieve such  indemnifying  party of any liability to
the indemnified party under this Section, but the omission so to deliver written
notice to the  indemnifying  party will not relieve it of any liability  that it
may have to any indemnified party otherwise than under this Section.

(d) if the  indemnification  provided  for in this Section is held by a court of
competent jurisdiction to be unavailable to an indemnified party with respect to
any losses,  claims, damages or liabilities referred to herein, the indemnifying
party, in lieu of indemnifying such indemnified  party thereunder,  shall to the
extent permitted by applicable law,  contribute to the amount paid or payable by
such indemnified party as a result of such loss,  claim,  damage or liability in
such  proportion  as is  appropriate  to  reflect  the  relative  fault  of  the
indemnifying  party on the one hand and of the indemnified party on the other in
connection with the Violation(s)  that resulted in such loss,  claim,  damage or
liability, as well as any other relevant equitable considerations.  The relative
fault of the indemnifying party and of the indemnified party shall be determined
by  reference  to,  among other  things,  whether  the untrue or alleged  untrue
statement  of a material  fact or the  omission  or alleged  omission to state a
material fact relates to information  supplied by the  indemnifying  party or by
the indemnified  party and the parties'  relative intent,  knowledge,  access to
information and opportunity to correct or prevent such statement or omission. No
person or entity guilty of fraudulent  misrepresentation  (within the meaning of

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Section 11 of the  Securities  Act) shall be entitled to  contribution  from any
person  or  entity   who  shall  not  have  been   guilty  of  such   fraudulent
misrepresentation.

(e)      the obligation of the Company, the Investors and MJK under this Section
         shall  survive the  completion  of any offering for resale of shares of
         the Registrable Stock in the Registration Statement, and otherwise.

9. Limitation on Subsequent Registration Rights. From and after the date of this
Agreement, the Company shall not, without the prior written consent of Investors
holding a majority of the  Registrable  Stock,  enter into any agreement,  which
might cause a reduction in the number of shares  includable  by the Investors in
any registration pursuant to Section 2 above.

10.  Successors  and Assigns.  The terms and  conditions of this  Agreement will
inure to the benefit of and be binding upon and be enforceable by the respective
heirs, successors and assigns of the parties hereto; provided, however, that the
rights of an Investor hereunder may be assigned only (a) to a partner or retired
partner of the assigning Investor,  if such assigning Investor is a partnership,
(b) to any Affiliate of the assigning Investor,  (c) to any family member of, or
any trust for the benefit of a family  member of the  assigning  Investor or (d)
concurrent  with the sale or transfer to such assignee of at least 50,000 shares
of Registrable Stock (subject to adjustment for any stock dividend, stock split,
subdivision,  combination or other recapitalization of the Company) then held by
the  assigning  Investor;  provided,  however,  that the  Company  is,  within a
reasonable  time after such transfer,  furnished with written notice of the name
and  address  of the  assignee  and the  securities  with  respect to which such
registration  rights are being assigned and such transferee agrees in writing to
be bound by and  subject  to the terms and  conditions  of this  Agreement.  Any
Investor or MJK making an assignment in connection  with the sale or transfer of
only a portion of its shares will retain its rights under this Agreement for the
shares not sold or transferred.  Nothing in this Agreement,  express or implied,
is  intended to confer  upon any party,  other than the parties  hereto or their
permitted  successors  and  assigns,  any  rights,   remedies,   obligations  or
liabilities under or by reason of this Agreement,  except as expressly  provided
in this Agreement.  Notwithstanding  any provision  contained  elsewhere in this
Agreement,  upon the transfer of shares by any of the parties hereto,  no claims
or causes of action arising out of or related to this  Agreement  existing as of
the  transfer  date will be  transferred  by such party to any heir,  successor,
assign or permitted transferee, provided that the transfer of shares will not be
deemed a waiver by the transferring party of any such claim or cause of action.

11.      Miscellaneous.

(a)      The Company shall not hereafter  enter into any agreement  with respect
         to its securities that is  inconsistent  with the rights granted to the
         Investors in this Agreement.

(b)      Except as otherwise  provided herein,  the provisions of this Agreement
         may not be amended,  modified or supplemented,  and waivers or consents
         to or departures  from the  provisions  hereof may not be given or made
         unless the Company has  obtained the written  consent of the  Investors
         and MJK holding at least a majority of the Registrable Stock.
<PAGE>

(c)      All  notices  and  other  communications   provided  for  or  permitted
         hereunder shall be made by hand delivery,  telex, facsimile,  overnight
         courier or registered first-class mail:

           (i)      if to an Investor, at the address set forth on Schedule A
                    attached hereto;

           (ii)     if to MJK, at the address set forth in the Stock Purchase
                    Agreement.

           (iii)    if to the Company, at the address set forth in the Purchase
                    Agreement.

         All such notices and  communications  shall be deemed to have been duly
         given: when delivered,  if by hand, overnight courier or mail; when the
         appropriate answer back is received,  if by telex; when transmission is
         confirmed by the sending unit, if by facsimile.

(d)      This Agreement may be executed in any number of counterparts and by the
         parties hereto in separate counterparts, each of which when so executed
         shall be deemed to be an original and all of which taken together shall
         constitute one an the same agreement.

(e)      The headings to this  Agreement are for  convenience  of reference only
         and shall not limit or otherwise affect the meaning hereof.

(f) This  Agreement  shall be governed by and construed in  accordance  with the
laws of the State of Minnesota without giving effect to the principles of choice
or conflict of law thereof.  Each of the Company and the  Investors  irrevocably
consent to the exclusive  jurisdiction  of the United States  Federal courts and
state courts, located in Hennepin County,  Minnesota,  in any suit or proceeding
relating to, based on or arising under this Agreement and irrevocably agree that
all claims in  respect  of such suit or  proceeding  may be  determined  in such
courts.  The Company  irrevocably waives the defense of an inconvenient forum to
the  maintenance of such suit or  proceeding.  Service of process on the Company
mailed by first class mail shall be deemed in every respect effective service of
process upon the Company in any such suit or  proceeding.  Nothing  herein shall
affect the right of any  Investor to serve  process in any manner  permitted  by
law.

(g)      In the event that any one or more of the provisions  contained  herein,
         or the  application  thereof  in any  circumstances,  is held  invalid,
         illegal or unenforceable  in any respect for any reason,  the validity,
         legality and  enforceability  of such  provision in every other respect
         and of the remaining  provisions  contained  herein shall not be in any
         way  impaired  thereby,  it being  intended  that all of the rights and
         privileges of the Investors and the Company shall be enforceable to the
         fullest extent permitted by law.

(h)      The remedies  provided for in this Agreement shall be cumulative and in
         addition  to all other  remedies  available,  at law or in equity,  and

<PAGE>

         nothing  herein shall limit a holder's  right to pursue actual  damages
         for any  failure  by the  Company  to  comply  with  the  terms of this
         Agreement.

(i)      This  Agreement,  the  documents  referenced  herein  and the  exhibits
         thereto,  constitute  the entire  understanding  and  agreement  of the
         parties  hereto with respect to the subject  matter  hereof and thereof
         and   supersede   all   prior   and   contemporaneous   agreements   or
         understandings,  inducements or conditions, express or implied, written
         or oral,  between the parties  with  respect  hereto and  thereto.  The
         express terms hereof control and supersede any course of performance or
         usage of the trade inconsistent with any of the terms hereof.
<PAGE>

         IN WITNESS WHEREOF,  the parties have executed this Registration Rights
Agreement as of the date first written above.

                              COMPANY:

                              MEDTOX SCIENTIFIC, INC.

                              By:
                                  ---------------------------------------------
                                   Name:
                                   Title:

                              MILLER, JOHNSON & KUEHN, INC.

                              By:
                                  ---------------------------------------------
                                   Name:
                                   Title:Exhibit 10.51
                            STOCK PURCHASE AGREEMENT

         This  Agreement  is made and  entered  into as of the 31st day of July,
2000,  between MEDTOX Scientific,  Inc., a Delaware  corporation (the "Company")
and  each  of  the  persons   listed  on  Schedule  1  to  this  Agreement  (the
"Investors").

         For good and valuable consideration,  the receipt and adequacy of which
are hereby  acknowledged  by the Company and each of the Investors,  the Company
and the Investors agree as follows:

            1.  Sale and  Purchase  of  Securities.  Subject  to the  terms  and
conditions  hereof,  the Company  agrees to sell to each Investor at the Closing
(as defined  herein),  and each Investor  severally  agrees to purchase from the
Company at the Closing,  at a purchase price of $10.00 per Unit,  that number of
Units set forth  opposite  each  Investor's  name on  Schedule  1 each such Unit
consisting of one share of the Company's  Common Stock (the "Shares"),  together
with  a  five-year  warrant  in the  form  attached  hereto  as  Exhibit  A (the
"Warrant") to purchase  that number of the Company's  Common Stock (the "Warrant
Shares")  set forth on Schedule 1 at an exercise  price of the higher of (a) the
share weighted  average closing bid price of the Company's  Common Stock for the
five trading  days  immediately  prior to the Closing (as defined  below) or (b)
$12.50 per warrant  share.  The Shares and the  Warrants  are referred to herein
collectively as the "Securities."

            2.  Closing.  The  closing  shall  take  place  at  the  offices  of
Fredrikson  &  Byron,  1100  International  Centre,  900  Second  Avenue  South,
Minneapolis, MN 55402 on July 31st, 2000 at 10:00 a.m. (the "Closing") and/or at
such other place or time as may be mutually  acceptable to the Investors and the
Company.  At the  Closing,  subject to the  satisfaction  of the  conditions  in
Section 6 below,  the  Company  will  deliver  to each  Investor  a  certificate
representing  the Shares  purchased by such  Investor,  together  with a Warrant
representing  the right to purchase that number of shares of Common Stock of the
Company set forth opposite each  Investor's  name on Schedule 1, against payment
of the  purchase  price  therefor  by  certified  check or wire  transfer to the
Company in the  amounts set forth  after  their  respective  names in Schedule 1
hereto.

            3.  Representations  and  Warranties by the Company.  To induce each
Investor to enter into this  Agreement  and to purchase the number of Securities
set forth after his or its name on Schedule 1, the Company hereby represents and
warrants to each Investor that except as set forth in Exhibit B hereto:

3.1  Organization,  Standing,  Etc. The Company is a corporation duly organized,
validly  existing and in good standing  under the laws of the State of Delaware,
and has the requisite corporate power and authority to own its properties and to
carry on its business in all material respects as it is now being conducted. The
Company is duly qualified to do business as a foreign corporation and is in good
standing in all states or  jurisdictions  in which the ownership or lease of its
property or the conduct of its  business  requires  such  qualification  and the
failure  to be so  qualified  would  have a  materially  adverse  effect  on the
Company's business.

3.2 Authorization and  Enforceability.  The Company has full legal power,  right
and authority to enter into this Agreement and the Registration Rights Agreement

<PAGE>

among the Company  and the  Investors,  the form of which is attached  hereto as
Exhibit C (the  "Registration  Rights  Agreement")  and to issue the Securities.
This Agreement, the Registration Rights Agreement and the Securities,  have been
duly  authorized,  executed  and  delivered on behalf of the Company and are the
valid and binding  obligations of the Company,  enforceable  in accordance  with
their respective terms and subject, as to enforcement, to applicable bankruptcy,
insolvency,  reorganization,  moratorium  and other laws affecting the rights of
creditors  generally,   to  the  exercise  of  judicial  discretion  as  to  the
availability  of equitable  remedies such as specific  performance in injunction
and subject, as to enforcement of the indemnification provisions, to limitations
under applicable  securities laws. The Securities when delivered pursuant to the
terms of this Agreement will be validly issued, fully paid and nonassessable.

3.3 Financial  Statements.  The financial  statements  included in the Company's
annual  reports on Form 10-K for the years ended  December 31, 1998 and 1999 and
for the quarter ended March 31, 2000:  (a) are in accordance  with the books and
records of the  Company,  (b)  present  fairly the  financial  condition  of the
Company at the balance  sheet dates and the  results of its  operations  for the
periods therein specified, and (c) have, in all material respects, been prepared
in accordance with generally accepted  accounting  principles applied on a basis
consistent with prior accounting periods. Without limiting the generality of the
foregoing, the balance sheet of the Company at December 31, 1999 included in the
Company's  annual  report on Form 10-K for the year ended  December 31, 1999 and
the balance  sheet of the Company at March 31,  2000  included in the  Company's
Report on Form 10-Q for the quarter ended March 31, 2000,  each discloses all of
the debts, liabilities and obligations of any nature (whether absolute,  accrued
or  contingent  and whether due or to become due) of the Company at December 31,
1999,  and March 31, 2000,  respectively,  which in  accordance  with  generally
accepted  accounting  principles  would be required to be disclosed in each such
balance sheet. To the Company's knowledge,  there are no material liabilities of
the Company which are not disclosed on such balance sheet.

3.4 Tax Returns and Audits.  All required  federal,  state and local tax returns
and  appropriate  extension  requests  of the Company  have been filed,  and all
federal,  state and local taxes required to be paid with respect to such returns
have been paid or due  provision  for the  payment  thereof  has been made.  The
Company is not delinquent in any material respect in the payment of any such tax
or in the payment of any assessment or governmental  charge. The Company has not
received  notice of any tax deficiency  proposed or assessed  against it, and it
has not executed any waiver of any statute of  limitations  on the assessment or
collection of any tax.

3.5 Changes,  Dividends,  Etc. Except for the transactions  contemplated by this
Agreement,  since  December 31, 1999 and except as set forth in Exhibit B or the
Company's reports filed under federal  securities laws, the Company has not: (i)
incurred any material debts,  obligations or liabilities,  absolute,  accrued or
contingent and whether due or to become due, except current liabilities incurred
in the ordinary course of business which (individually or in the aggregate) will
not materially and adversely affect the business, properties or prospects of the
Company;  (ii)  paid  any  material  obligation  or  liability  other  than,  or
discharged  or satisfied  any material  liens or  encumbrances  other than those
securing, current liabilities,  in each case in the ordinary course of business;
(iii) declared or made any payment to or  distribution  to its  shareholders  as
such, or purchased or redeemed any of its shares of capital stock,  or obligated
itself to do so; (iv) mortgaged,  pledged or subjected to lien, charge, security
interest  or  other  encumbrance  any  of  its  material  assets,   tangible  or

<PAGE>

intangible,  except in the ordinary course of business; (v) sold, transferred or
leased any of its material  assets  except in the  ordinary  course of business;
(vi) suffered any physical  damage,  destruction or loss (whether or not covered
by  insurance)  materially  and  adversely  affecting  the tangible  properties,
business or prospects of the Company;  (vii) encountered any labor  difficulties
or labor  union  organizing  activities;  (viii)  issued  or sold any  shares of
capital  stock or  other  securities  or  granted  any  options  (other  than to
employees or directors), warrants, or other purchase rights with respect thereto
other than pursuant to this Agreement;  (ix) made any acquisition or disposition
of any material  assets or became  involved in any other  material  transaction,
other than for fair value in the  ordinary  course of business;  (x)  materially
increased  the  compensation  payable,  or to  become  payable,  to  any  of its
directors  or  employees,  or made any  material  cash bonus  payment or similar
arrangement  with any directors or employees or increased the scope or nature of
any fringe benefits provided of its employees or directors; or (xi) agreed to do
any of the foregoing other than pursuant hereto.  Except as set forth in Exhibit
B,  there  has been no  material  adverse  change  in the  financial  condition,
operations,  results of  operations,  business or prospects of the Company since
December 31, 1999.

3.6 Title to Properties  and  Encumbrances.  The Company has good and marketable
title to all of the  properties  and assets that it purports to own,  except for
property disposed of in the ordinary course of business since December 31, 1999,
which  properties  and assets are not subject to any  mortgage,  pledge,  lease,
lien, charge,  security interest,  encumbrance or restriction,  except (a) those
which are shown and  described on the  December  31, 1999  balance  sheet or the
notes thereto, (b) liens for taxes and assessments or other governmental charges
or levies not at the time due or in respect of which the validity  thereof shall
currently be contested in good faith by appropriate  proceedings,  (c) statutory
liens that have arisen in the ordinary course of business, or (d) those which do
not  materially  affect  the  value  of or  interfere  with the use made of such
properties and assets.

3.7 Conditions.  The plant,  offices and equipment of the Company have been kept
in good condition and repair in the ordinary course of business.

3.8 Litigation;  Governmental  Proceedings.  There are no legal actions,  suits,
arbitrations  or other legal,  administrative  or  governmental  proceedings  or
investigations  pending or, to the knowledge of the Company,  threatened against
the Company,  or its  properties or business  which would result in any material
adverse  change  in the  business,  assets,  liabilities,  financial  condition,
operations or prospects of the Company nor, to the knowledge of the Company,  is
there any basis for any such legal actions, suits,  arbitrations or proceedings.
The Company is not in default with respect to any  judgment,  order or decree of
any court or any governmental agency or instrumentality with respect to which it
is a party or is named as an affected  person,  nor to the best of its knowledge
is the Company in default with respect to any other  judgment,  order or decree.
The  Company has not been  threatened  with any action or  proceeding  under any
business, regulatory or zoning ordinance, law or regulation.

3.9 Compliance  With Applicable  Laws or Other  Instruments.  To the best of the
Company's  knowledge,  the business and  operations of the Company have been and
are being  conducted in all material  respects in accordance with all applicable
laws,  rules and  regulations  of all  governmental  authorities,  except to the
extent  that any  failure to so  conduct  its  business  would not result in any
material  adverse  change  in  the  business,  assets,  liabilities,   financial
condition, operations or prospects of the Company.
<PAGE>

3.10 Shares,  Warrants and Warrant Shares. The Shares and Warrants,  when issued
and paid for pursuant to the terms of this Agreement,  will be duly  authorized,
validly issued and outstanding,  fully paid and  nonassessable and shall be free
and  clear  of  all  pledges,  liens,  encumbrances  and  restrictions,   except
securities  restrictions  as set forth in Section 4 hereof.  The Warrant  Shares
have been  reserved for issuance and when issued upon  exercise of the Warrants,
will  be  duly  authorized,   validly  issued  and   outstanding,   fully  paid,
nonassessable  and  free and  clear  of all  pledges,  liens,  encumbrances  and
restrictions, except as set forth in Section 4.

3.11 Securities Laws. Based in part upon the  representations  of the Investors,
no  consent,  authorization,  approval,  permit or order of or  filing  with any
governmental  or  regulatory  authority  is  required  under  current  laws  and
regulations  in connection  with the execution and delivery of this Agreement or
the  offer,  issuance,  sale or  delivery  of the  Securities,  other  than  the
qualification  thereof,  if required,  under  applicable  state securities laws,
which  qualification has been or will be effected as a condition of these sales.
The Company has not, directly or through an agent, offered the Securities or any
similar  securities  for sale to,  or  solicited  any  offers  to  acquire  such
securities  from,   persons  other  than  the  Investors  and  other  accredited
investors.  Under the circumstances  contemplated by this Agreement,  the offer,
issuance,  sale and delivery of the Securities  will not, under current laws and
regulations,  require  compliance  with the prospectus  delivery or registration
requirements of the federal  Securities Act of 1933, as amended (the "Securities
Act").  The  Company  has for the prior 12 months  filed  all  reports  or other
documentation that it is required to file by the federal Securities Exchange Act
of 1934,  as amended  (the "1934  Act"),  any rules or  regulations  promulgated
thereunder,  the applicable rules and regulations of the National Association of
Securities  Dealers ("NASD"),  and the information  contained in such reports or
other documents,  as of their  respective  filing dates, did not make any untrue
statement of a material fact or omit to state a material fact necessary in order
to make the statements made, in the light of the circumstances  under which they
were made, not misleading.

3.12 Patents and Other  Intangible  Rights.  To the best of its  knowledge,  the
Company (a) owns or has the right to use, free and clear of all material  liens,
claims and restrictions,  all patents,  trademarks,  service marks, trade names,
copyrights,  licenses  and rights  with  respect to the  foregoing,  used in the
conduct of its business as now conducted  without  infringing  upon or otherwise
acting  adversely  to the right or  claimed  right of any  person  under or with
respect to any of the  foregoing,  and,  to the extent such right on the part of
the Company is  non-exclusive,  such  non-exclusivity  has no  material  adverse
effect on the  business of the  Company as  currently  conducted,  (b) except as
disclosed in the Company's  reports filed under the  Securities  Act or the 1934
Act, is not obligated or under any liability  whatsoever to make any payments of
a  material  nature  by way of  royalties,  fees or  otherwise  to any owner of,
licensor of, or other claimant to, any patent, trademark,  trade name, copyright
or other intangible asset, with respect to the use thereof or in connection with
the conduct of its business or otherwise, (c) owns or has the unrestricted right
to use all  trade  secrets,  including  know-how,  customer  lists,  inventions,
designs,  processes,  computer  programs  and  technical  data  necessary to the
development, operation and sale of all products and services sold or proposed to
be sold by it, free and clear of any rights,  liens or claims of others, and (c)
is not using any confidential information or trade secrets of others.

3.13  Capital  Stock.  At the date  hereof,  the  Company is  authorized  by its
Certificate of Incorporation,  as amended,  to issue 7,450,000 shares of capital

<PAGE>

stock,  which consists of the following:  (a) 7,400,000  shares of common stock,
$0.15 par value, of which there are outstanding 2,935,720 shares, and (b) 50,000
shares or serial  Preferred Stock, of which no shares are issued or outstanding.
All of the  outstanding  shares of the  Company  were duly  authorized,  validly
issued and are fully paid and  nonassessable  and were issued in compliance with
applicable  securities  laws. Other than as disclosed on Exhibit B, there are no
outstanding  subscriptions,   options,  warrants,  calls,  contracts,   demands,
commitments,  convertible  securities or other agreements or arrangements of any
character or nature whatever, other than this Agreement, under which the Company
is  obligated  to issue any  securities  of any kind  representing  an ownership
interest in the Company.

3.14 License and Approvals. The Company has all licenses, certificates,  permits
and other approvals from governmental and regulatory  authorities  necessary for
the conduct of its business as it is currently  being  conducted and as proposed
to be conducted  except those which would not have a material  adverse effect on
the Company if not obtained.

3.15  Defaults.  The Company is not in breach,  default or violation of, and the
execution  of this  Agreement  and the  Registration  Rights  Agreement  and the
consummation  of the  transactions  herein  and  therein  contemplated  will not
conflict with or result in any breach of, any of the terms or conditions  of, or
constitute a default or violation under,  (i) the Certificate of  Incorporation,
as amended, or Bylaws, as amended, of the Company,  (ii) any material indenture,
agreement or other  instrument to which the Company is now a party,  or (iii) to
the best of the Company's  knowledge,  any law or any order,  rule or regulation
applicable  to the  Company of any court or of any  federal or state  regulatory
body or  administrative  agency  having  jurisdiction  over the  Company  or its
property.

3.16 Insurance Coverage. There are in full force policies of insurance issued by
insurers of recognized  responsibility  insuring the Company and its  properties
and  business  against  such losses and risks,  and in such  amounts,  as in the
Company's best judgment,  after advice from its insurance broker, are acceptable
for the nature and extent of such business and its resources.

3.17 No Brokers or  Finders.  Except for Miller,  Johnson & Kuehn,  Incorporated
(the  "Sales  Agent"),  which  is  assisting  the  Company  in the  transactions
contemplated by this Agreement, no person, firm or corporation has or will have,
as a result of any act or omission of the Company, any right,  interest or valid
claim  against  the Company or any  Investor  for any  commission,  fee or other
compensation  as  a  finder  or  broker  in  connection  with  the  transactions
contemplated by this Agreement.  The Company will indemnify and hold each of the
Investors  harmless  against  any and all  liability  with  respect  to any such
commission,  fee or other  compensation which may be payable or determined to be
payable in connection with the transactions contemplated by this Agreement.

3.18 Disclosure.  The Company has not knowingly  withheld from the Investors any
material facts relating to the assets, business, operations, financial condition
or prospects of the Company.  No representation or warranty in this Agreement or
in any certificate,  schedule or other document  furnished or to be furnished to
any Investor pursuant hereto or in connection with the transactions contemplated
hereby contains or will contain any untrue statement of a material fact or omits
or will omit to state any material  fact required to be stated herein or therein
or necessary to make the statements herein or therein not misleading.
<PAGE>

         3.19  Company  Knowledge.  For  purposes  of  this  Section  3,  when a
representation  or warranty is qualified by the Company's  "knowledge"  or "best
knowledge,"  such  representation  or  warranty  is  based  upon  the  Company's
knowledge after due inquiry.

4. Representations of the Investors.  Each Investor represents for itself that:

4.1 Investment  Intent. The Securities being acquired by such Investor are being
purchased for investment  for such  Investor's own account and not with the view
to, or for  resale in  connection  with,  any  distribution  or public  offering
thereof.  Such Investor understands that the Securities have not been registered
under  the  Securities  Act or any  state  securities  laws by  reason  of their
contemplated issuance in transactions exempt from the registration  requirements
of the  Securities  Act and  applicable  state  securities  laws,  and  that the
reliance of the Company and others upon these  exemptions  is predicated in part
upon this  representation by each Investors.  Such Investor further  understands
that the Securities  may not be  transferred or resold without (i)  registration
under the Securities Act and any applicable  state  securities  laws, or (ii) an
exemption from the  requirements  of the  Securities  Act and  applicable  state
securities laws.

         Such Investor  understands that an exemption from such  registration is
presently available pursuant to Rule 144 promulgated under the Securities Act by
the Securities and Exchange  Commission (the "Commission") but that in any event
an  Investor  may not  sell any  securities  pursuant  to Rule 144  prior to the
expiration  of  a  one-year   period  after  such  Investor  has  acquired  such
securities. Such Investor understands that any sales pursuant to Rule 144 can be
made only in full compliance with the provisions of Rule 144.

4.2 Location of Principal Office,  Qualification as an Accredited Investor, Etc.
The state in which  such  Investor's  principal  office  (or  domicile,  if such
Investor is an individual) is located is the state set forth in such  Investor's
address on Schedule 1. Unless otherwise  indicated on such Investor's  signature
page to this Agreement,  such Investor qualifies as an "accredited investor" for
purposes of Regulation D promulgated  under the  Securities  Act for the reasons
specified  after such  investor's  name on such  signature  page.  Such Investor
acknowledges  that  the  Company  has  made  available  to  such  Investor  at a
reasonable  time prior to the execution of this Agreement the opportunity to ask
questions and receive answers concerning the business and affairs of the Company
and the terms and  conditions  of the sale of  securities  contemplated  by this
Agreement and to obtain any additional  information (which the Company possesses
or can acquire  without  unreasonable  effort or expense) as may be necessary to
verify the accuracy of information furnished to such Investor. Such Investor (a)
is able to bear the loss of its  entire  investment  in the Shares  without  any
material  adverse effect on its business,  operations or prospects,  and (b) has
such  knowledge  and  experience  in financial  and business  matters that it is
capable of  evaluating  the merits and risks of the  investment to be made by it
pursuant to this Agreement.

4.3  Acts and  Proceedings.  This  Agreement  has been  duly  authorized  by all
necessary  action  on the part of such  Investor,  has been  duly  executed  and
delivered  by  such  Investor,  and is a valid  and  binding  agreement  of such
Investor.

4.4 No Brokers or Finders.  Except for the Sales Agent,  which is assisting  the
Company in the transactions  contemplated by this Agreement,  no person, firm or
corporation  has or  will  have,  as a  result  of any act or  omission  by such

<PAGE>

Investor,  any right,  interest  or valid  claim  against  the  Company  for any
commission,  fee or other  compensation as a finder or broker, or in any similar
capacity,  in connection with the  transactions  contemplated by this Agreement.
Such Investor will indemnify and hold the Company  harmless  against any and all
liability with respect to any such commission,  fee or other  compensation which
may be payable or  determined  to be payable as a result of the  actions of such
Investor in connection with the transactions contemplated by this Agreement.

4.5 Exculpation Among Investors.  Such Investor  acknowledges that in making his
or its decision to invest in the  Company,  he or it is not relying on any other
Investor  or upon any person,  firm or  company,  other than the Company and its
officers,  employees  and/or  directors.  Such  Investor  agrees  that no  other
Investor,  nor the partners,  employees,  officers or controlling persons of any
other  Investor  shall be liable  for any  actions  taken by such  Investor,  or
omitted to be taken by such Investor, in connection with such investment.

4.6 Legends.  It is understood that the  certificates  evidencing the Shares may
bear legends required by applicable federal and state securities laws as well as
the following legend:

         THE SECURITIES  REPRESENTED BY THIS  CERTIFICATE HAVE BEEN ACQUIRED FOR
         INVESTMENT  AND HAVE NOT BEEN  REGISTERED  UNDER THE  SECURITIES ACT OF
         1933, AS AMENDED.  THESE  SECURITIES  MAY NOT BE SOLD OR TRANSFERRED IN
         THE ABSENCE OF SUCH  REGISTRATION  OR AN  EXEMPTION  FROM  REGISTRATION
         UNDER THE SECURITIES ACT OF 1933 AND APPLICABLE  STATE SECURITIES LAWS.
         ADDITIONALLY,  THE  TRANSFER  OF THESE  SECURITIES  IS  SUBJECT  TO THE
         CONDITIONS  SPECIFIED IN THE  REGISTRATION  RIGHTS AGREEMENT DATED JULY
         31st, 2000, AMONG MEDTOX SCIENTIFIC, INC. AND CERTAIN OTHER SIGNATORIES
         THERETO,  AND NO  TRANSFER  OF  THESE  SECURITIES  SHALL  BE  VALID  OR
         EFFECTIVE UNTIL SUCH CONDITIONS HAVE BEEN FULFILLED.

            5.  Conditions  of Each  Investor's  Obligation.  The  obligation to
purchase and pay for the  Securities  which each Investor has agreed to purchase
on the  closing  date is subject to the  fulfillment  prior to or on the closing
date of the conditions set forth in this Article 5.

5.1  Representations  and Warranties.  The representations and warranties of the
Company under this  Agreement  shall be true in all material  respects as of the
closing date with the same effect as though made on and as of the closing date.

5.2 Compliance with Agreement.  The Company shall have performed and complied in
all  material  respects  with all  agreements  or  conditions  required  by this
Agreement to be performed and complied with prior to or as of the closing date.

5.3 Certificate of Officers. The Company shall have delivered to Miller, Johnson
& Kuehn, Incorporated, on behalf of Investors, a certificate,  dated the closing
date, executed by the Chief Executive Officer and the Chief Financial Officer of
the Company and certifying to the  satisfaction  of the conditions  specified in
Sections 5.1 and 5.2.
<PAGE>

5.4 Opinion of the  Company's  Counsel.  The  Company  shall have  delivered  to
Miller,  Johnson & Kuehn,  Incorporated,  on behalf of Investors,  an opinion of
Fredrikson & Byron,  counsel for the  Company,  dated the closing  date,  to the
effect that:

(a)      The Company is a corporation  duly  organized  and validly  existing in
         good standing under the laws of the state of its incorporation, and has
         the corporate power and authority to own and hold the properties  owned
         and leased by it and to carry on the  business  in which it is engaged.
         The Company has the  corporate  power and  authority to enter into this
         Agreement,  to  issue  and  sell the  Securities  and to carry  out the
         provisions of this Agreement.

(b)      This Agreement has been duly authorized,  executed and delivered by the
         Company,  and is the legal,  valid and binding agreement of the Company
         and is  enforceable  against the Company in accordance  with its terms,
         subject,  as to the  enforcement  of  remedies,  to  limitations  under
         applicable  bankruptcy,  insolvency,  moratorium,  reorganization,  and
         other laws affecting the rights of creditors  generally and to judicial
         limitations on the  enforcement  of the remedy of specific  performance
         and other equitable remedies.

(c)      The  Securities  being  purchased  on the  closing  date have been duly
         authorized, validly issued and delivered by the Company, are fully paid
         and  nonassessable,  and are  entitled to the rights,  preferences  and
         provisions  of the  Company's  Certificate  of  Incorporation  and  the
         benefits of the provisions of this Agreement  applicable  thereto.  The
         certificates  evidencing  the  Shares and the  Warrants  are in due and
         proper form.

(d)      All corporate  proceedings required by law or by the provisions of this
         Agreement to be taken by the Board of Directors and shareholders of the
         Company  on or  prior  to such  closing  date in  connection  with  the
         execution and delivery of this Agreement,  the offer, issuance and sale
         of the Securities and the consummation of the transactions contemplated
         by this Agreement, have been duly and validly taken.

(e) The Company is authorized by its Certificate of  Incorporation,  as amended,
to issue 7,450,000 shares of capital stock, which consists of the following: (a)
7,400,000  shares  of  common  stock,  $0.15  par  value,  of  which  there  are
outstanding 2,935,720 shares, and (b) 50,000 shares of serial preferred stock of
which no  shares  were  issued  or  outstanding.  To the best of such  counsel's
knowledge,  all shares  outstanding  immediately  prior to the closing date have
been duly authorized and validly  issued.  Other than as disclosed on Exhibit B,
the Company has no other authorized series or class of capital stock and, to the
best of such  counsel's  knowledge  and without any  special  inquiry  into this
matter,  has no  outstanding  options,  warrants  or  other  rights  to  acquire
securities of the Company.

(f)      The requisite number of Warrant Shares have been validly authorized and
         reserved for issuance upon  exercise of the  Warrants,  and when issued
         upon such exercise in accordance  with the terms and  conditions of the
         Warrants,  will be authorized,  validly issued and  outstanding,  fully
         paid and  nonassessable.  To the best of such counsel's  knowledge,  no

<PAGE>

         security  holder of the Company is entitled  to  preemptive  or similar
         rights as a result of the  execution  or delivery of this  Agreement or
         the issuance of the Securities.

(g) Assuming (i) the accuracy of the  representations  made by the  Investors in
their Acceptances and Section 4 hereof, (ii) that neither the Company, the Sales
Agent nor any person  acting on behalf of either the  Company or the Sales Agent
offered or sold the  Securities by any form of general  solicitation  or general
advertising  within  the  meaning  of Rule  502(c)  of  Regulation  D under  the
Securities Act; (iii) that any person or entity that purchases  securities after
the date hereof in a transaction that can be "integrated"  with the sales of the
Securities will be an accredited  investor as of the date of such purchase;  and
(iv) that, based upon our inquiry and information provided to us by the Company,
each person or entity that purchased securities of the Company directly from the
Company or its agents and without registration between the date six months prior
to the  Closing  and the  date of this  Agreement  was,  as of the  date of such
purchase,  an "accredited  investor" as defined in Rule 501 of Regulation D, the
sale,  issuance  and  delivery  of the  Securities  to the  Investors  under the
circumstances  contemplated  by this Agreement are exempt from the  registration
and prospectus delivery requirements of the Securities Act.

(h)      Except  for  matters  disclosed  in  Exhibit  B,  such  counsel  has no
         knowledge  of  any  material  litigation,  proceeding  or  governmental
         investigation   pending  or  threatened  against  the  Company  or  its
         properties or business.

5.5      Supporting  Documents.  The Sales Agent,  as  representatives  for
         each investor,  shall have received the following:

(a)      A copy  of  resolutions  of  the  Board  of  Directors  of the  Company
         certified by the Secretary of the Company authorizing and approving the
         execution,  delivery and  performance of this Agreement and issuance of
         the Securities;

(b)      A certificate  of  incumbency  executed by the Secretary of the Company
         certifying the names,  titles and signatures of the officers authorized
         to execute this Agreement and further  certifying  that the Certificate
         of Incorporation  and Bylaws of the Company  delivered to legal counsel
         for the Investors at the time of the execution of this  Agreement  have
         been validly adopted and have not been amended or modified;

(c)      The certificates contemplated by Section 5.3 above; and

(d)      Such additional  supporting  documentation  and other  information with
         respect to the  transactions  contemplated  hereby as legal counsel for
         the Investors may reasonably request.

5.6   Qualification    Under   State   Securities   Laws.   All   registrations,
qualifications, permits and approvals required under applicable state securities
laws for the lawful  execution  and  delivery of this  Agreement  and the offer,
sale,  issuance and delivery of the  Securities  to the Investors at the closing
shall have been obtained.
<PAGE>

5.7 Proceeding and Documents.  All corporate and other  proceedings  and actions
taken  in  connection  with  the  transactions   contemplated   hereby  and  all
certificates,  opinions, agreements,  instruments and documents mentioned herein
or incident to any such transaction  shall be satisfactory in form and substance
to legal counsel for the Investors.

5.8 Registration  Rights Agreement.  The Company,  each Investor and each of the
parties  listed  on the  signature  page of  Exhibit  C  shall  enter  into  the
Registration  Rights  Agreement  dated as of the Closing in the form attached as
Exhibit C.

6.  Conditions of the Company's  Obligations at Closing.  The obligations of the
Company to each Investor under this Agreement are subject to the  fulfillment on
or before the Closing of each of the following conditions by that Investor.

6.1  Representations  and Warranties.  The representations and warranties of the
Investor  contained in Section 4 shall be true on and as of the Closing with the
same effect as though such  representations  and warranties had been made on and
as of the Closing.

6.2 Payment of Purchase  Price.  The Investors shall have delivered the purchase
price as specified in Section 1.

7.  Affirmative  Covenants of the Company.  The Company  covenants and agrees as
follows:

7.1 Corporate  Existence.  The Company will maintain its corporate  existence in
good standing and comply with all applicable  laws and regulations of the United
States or of any state or political  subdivision  thereof and of any  government
authority where failure to so comply would have a material adverse impact on the
Company or its business or operations.

7.2 Books of Accounts  and  Reserves.  The Company will keep books of record and
account  in  which  full,  true  and  correct  entries  are  made  of all of its
respective dealings, business and affairs, in accordance with generally accepted
accounting principles. The Company will employ certified public accountants that
are  "independent"  within the  meaning  of the  accounting  regulations  of the
Securities and Exchange Commission.

7.3 Application of Proceeds. Unless otherwise approved by the Investors, the net
proceeds received by the Company from the sale of the Shares on the closing date
shall be used for research and  development,  expansion of sales,  marketing and
manufacturing  capabilities,  and working  capital and other  general  corporate
purposes (without allocation of any specific amount to any of the foregoing).

7.4 Filing of Reports.  The Company will make timely  filings of such reports as
are  required to be filed by it with the  Commission  so that Rule 144 under the
Securities  Act or any  successor  provision  thereto  will be  available to the
security holders of the Company who were otherwise able to take advantage of the
provisions of such Rule.

7.5 Patents and Other Intangible  Rights.  The Company will apply for, or obtain
assignments  of, or licenses to use,  all patents,  trademarks,  trade names and
copyrights  which in the  opinion of a prudent  and  experienced  businessperson

<PAGE>

operating  in the industry in which the Company is  operating  are  desirable or
necessary for the conduct and protection of the business of the Company.

7.6 Insurance.  The Company will maintain  insurance  against such losses and in
such amounts as the Company shall deem prudent.

8. Miscellaneous.

8.1 Notices. All notices,  requests,  consents and other communications required
or permitted  hereunder  shall be in writing and shall be  delivered,  or mailed
first-class postage prepaid, registered or certified mail:

(a) if to any holder of any Shares  addressed  to such  holder at its address as
shown on the books of the Company,  or at such other  address as such holder may
specify by written notice to the Company, or

(b) if to the Company at 402 West County Road D, St. Paul, MN 55112,  Attention:
Chief Executive Officer;  or at such other address as the Company may specify by
written notice to the Investors; or

(c) if to the Agent at 5500 Wayzata Boulevard, Minneapolis, MN 55416, or at such
other address as the Agent may specify by written notice to the Company.

and such  notices  and  other  communications  shall  for all  purposes  of this
Agreement  be  treated as being  effective  or having  been  given if  delivered
personally, or, if sent by mail, when received.

8.2 Survival of Representations  and Warranties,  Etc. All  representations  and
warranties  contained  herein shall  survive the  execution and delivery of this
Agreement,  any  investigation  at any time  made by the  Investors  or on their
behalf,  and the sale and  purchase  of the Shares  and  payment  therefor.  All
statements  contained in any certificate,  instrument or other writing delivered
by or on behalf of the  Company  pursuant  to this  Agreement  (other than legal
opinions) at the closing shall constitute  representations and warranties by the
Company hereunder.

8.3 Parties in Interest. All the terms and provisions of this Agreement shall be
binding upon and inure to the benefit of and be  enforceable  by the  respective
successors and assigns of the parties hereto,  whether so expressed or not, and,
in particular, shall inure to the benefit of and be enforceable by the holder or
holders  from  time to  time of any of the  Shares;  provided,  however,  that a
successor or assign of an Investor shall not be regarded as an "Investor."

8.4 Headings.  The headings of the articles and sections of this  Agreement have
been inserted for  convenience of reference only and do not constitute a part of
this Agreement.

8.5 Choice of Law.  The laws of  Minnesota  shall  govern the  validity  of this
Agreement,  the construction of its terms and the  interpretation  of the rights
and duties of the parties hereunder.
<PAGE>

8.6 Counterparts. This Agreement may be executed at different times by different
Investors  and in two or more  counterparts,  each of which  shall be  deemed an
original,  but  all  of  which  together  shall  constitute  one  and  the  same
instrument.  This Agreement may be executed and delivered by one or more parties
via facsimile transmission. Notwithstanding any other section of this Agreement,
the execution of this Agreement on different dates by different  Investors shall
not be deemed an amendment to this Agreement.

                      (Remainder of page intentionally left blank)

<PAGE>

         IN WITNESS  WHEREOF,  the  Company  has  caused  this  Agreement  to be
executed by its duly  authorized  representative  and each of the  Investors has
executed the acceptance form following the signature page.

COMPANY:                           MEDTOX SCIENTIFIC, INC.

                                   By:
                                     ------------------------------------------
                                   Its:
                                     ------------------------------------------

                  (Signature Page to Stock Purchase Agreement)

<PAGE>

                                   ACCEPTANCE

         THE  UNDERSIGNED  accepts  and agrees to the terms and  conditions  set
forth in the Stock  Purchase  Agreement  among MEDTOX  Scientific,  Inc. and the
persons  listed on Schedule 1 dated July 31st,  2000 (the  "Agreement").  By the
execution of this Acceptance,  the undersigned makes each of the representations
contained in Section 4 of the Agreement. The undersigned further represents that
the undersigned  qualifies as an "accredited  investor" as that terms is defined
in  Regulation  D under the  Securities  Act of 1933,  as amended  (the  "Act"),
because (check one):

Accredited  individual  investors  must  initial  one or both  of the  following
statements:

         _____    I  certify  that I am an  accredited  investor  because  I had
                  individual income (exclusive of any income  attributable to my
                  spouse) of more than  $200,000  in each of the most recent two
                  years or joint income with my spouse of more than  $300,000 in
                  each of such  years  and I  reasonably  expect to have such an
                  income in excess of such amounts for the current year.

         _____    I certify that I am an accredited  investor  because I have an
                  individual  net  worth,  or my  spouse  and I have a  combined
                  individual net worth, in excess of $1.0 million.  For purposes
                  of this Acceptance  "individual net worth" means the excess of
                  total assets at fair market value, including home and personal
                  property, over total liabilities.

         _____ I certify  that I am a director  or  executive  officer of MEDTOX
Scientific, Inc.

         Accredited  partnerships,  corporations  or other entities must initial
one or more of the following statements:

         _____    The  undersigned is a bank or savings and loan  association as
                  defined in Sections 3(a)(2) and 3(a)(5)(A),  respectively,  of
                  the Act acting either in its individual or fiduciary capacity.

         _____ The  undersigned  is an  insurance  company as defined in Section
2(13) of the Act.

          _____ The undersigned is an investment  company  registered  under the
     Investment Company Act of 1940 or a business development company as defined
     in Section 2(a)(48) of that Act.

         _____    The  undersigned  is  a  Small  Business   Investment  Company
                  licensed  by the  U.S.  Small  Business  Administration  under
                  Section 301(c) or (d) of the Small Business  Investment Act of
                  1958.

<PAGE>

         _____    The undersigned is an employee benefit plan within the meaning
                  of Title I of the Employee  Retirement  Income Security Act of
                  1974 and either (check one or more, as applicable):

                  _____ (a) the investment decision is made by a plan fiduciary,
                  as  defined in  Section  3(21) of such Act,  which is either a
                  bank,  savings and loan  association,  insurance  company,  or
                  registered investment adviser; or

                  _____ (b) the employee benefit plan has total assets
                   in excess of $5,000,000; or

                  _____ (c) the plan is a  self-directed  plan  with  investment
                  decisions   made  solely  by  persons   who  are   "Accredited
                  Investors" as defined under the Act.

         _____    The undersigned is a private  business  development  company
                  as defined in Section  202(a)(22) of the Investment Advisers
                  Act of 1940.

         _____    The undersigned has total assets in excess of $5,000,000,  was
                  not  formed  for  the  specific   purpose  of  acquiring   the
                  Securities  and is one or more of the following  (check one or
                  more, as appropriate):

                  _____ (a)     an organization described in Section
                                501(c)(3) of the Internal Revenue Code; or

                  _____ (b)     a corporation; or

                  _____ (c)     a Massachusetts or similar business trust; or

                  _____ (d)     a partnership.

         _____    The  undersigned  is  a  trust  with  total  assets  exceeding
                  $5,000,000,  which was not formed for the specific  purpose of
                  acquiring the  Securities  and whose purchase is directed by a
                  person who has such  knowledge and experience in financial and
                  business  matters that he or she is capable of evaluating  the
                  merits and risks of the investment in the Securities.

         The undersigned makes the following additional representation:

         This Agreement has been duly authorized by all necessary  action on the
part of the  undersigned,  has been duly  executed by an  authorized  officer or
representative of the undersigned,  and is a legal, valid and binding obligation
of the undersigned enforceable in accordance with its terms.

                                                  * * * * * * * *

<PAGE>

Total dollar amount of investment: $________________________

Number  of  Units  @  $10.00  per  Unit:  _________________________  (each  Unit
     consisting  of one share of Common Stock and a Warrant to purchase the same
     number of shares of Common Stock, subject to other adjustments as set forth
     in the Warrant)

                                  Dated: [Date]

        ENTITY INVESTORS                           INDIVIDUAL INVESTOR

----------------------------------------    -----------------------------------
 Name of Entity                              Signature

By: ____________________________________    ____________________________________
        Signature                            Signature of Joint Holder, if any
Its: __________________________________
       Title

-----------------------------------------    ----------------------------------
  Name Typed or Printed                      Name Typed or Printed

-----------------------------------------   -----------------------------------
Address to Which Correspondence             Address to Which Correspondence
should be Directed                          should be Directed

-----------------------------------------   -----------------------------------

-----------------------------------------   -----------------------------------
City, State and Zip Code                     City, State and Zip Code

-----------------------------------------   -----------------------------------
  Tax Identification Number                  Social Security Number

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