Exhibit 4.16

                                                                       EXHIBIT D

NEITHER THIS WARRANT NOR THE SHARES ISSUABLE UPON EXERCISE HEREOF HAVE BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT")
OR ANY OTHER APPLICABLE SECURITIES LAWS IN RELIANCE UPON AN EXEMPTION FROM THE
REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND SUCH OTHER SECURITIES LAWS.
NEITHER THIS WARRANT NOR THE SHARES ISSUABLE UPON EXERCISE HEREOF MAY BE SOLD,
PLEDGED, TRANSFERRED, ENCUMBERED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR IN A TRANSACTION
WHICH IS EXEMPT FROM REGISTRATION UNDER THE PROVISIONS OF THE SECURITIES ACT.

                             STOCK PURCHASE WARRANT

                  To Purchase 100,000 Shares of Common Stock of

                            Milestone Scientific Inc.

            THIS CERTIFIES that, for value received, Hillgreen Investments
Limited (the "Holder"), is entitled, upon the terms and subject to the
conditions hereinafter set forth, at any time on or after January 22, 2001 (the
"Initial Exercise Date") and on or prior to the close of business on January 22,
2004 (the "Termination Date") but not thereafter, to subscribe for and purchase
from Milestone Scientific Inc., a Delaware corporation (the "Company"), up to
100,000 shares (the "Warrant Shares") of Common Stock, $.001 par value, of the
Company (the "Common Stock"). The purchase price of one share of Common Stock
(the "Exercise Price") under this Warrant shall be $1.86. The Exercise Price and
the number of shares for which the Warrant is exercisable shall be subject to
adjustment as provided herein. Capitalized terms used and not otherwise defined
herein shall have the meanings set forth for such terms in that certain Private
Equity Line of Credit Agreement, dated January 19, 2001, between the Company and
Hillgreen Investments Limited (the "Purchase Agreement).
<PAGE>

            1. Title to Warrant. Prior to the Termination Date and subject to
compliance with applicable laws, this Warrant and all rights hereunder are
transferable, in whole or in part, at the office or agency of the Company by the
holder hereof in person or by duly authorized attorney, upon surrender of this
Warrant together with the Assignment Form annexed hereto properly endorsed.

            2. Authorization of Shares. The Company covenants that all shares of
Common Stock which may be issued upon the exercise of rights represented by this
Warrant will, upon exercise of the rights represented by this Warrant, be duly
authorized, validly issued, fully paid and nonassessable and free from all
taxes, liens and charges in respect of the issue thereof (other than taxes in
respect of any transfer occurring contemporaneously with such issue).

            3. Exercise of Warrant. Except as provided in Section 4 herein,
exercise of the purchase rights represented by this Warrant may be made at any
time or times on or after the Initial Exercise Date and before the close of
business on the Termination Date. Exercise of this Warrant or any part hereof
shall be effected by the surrender of this Warrant and the Notice of Exercise
Form annexed hereto duly executed, at the office of the Company (or such other
office or agency of the Company as it may designate by notice in writing to the
registered holder hereof at the address of such holder appearing on the books of
the Company) and upon payment of the Exercise Price of the shares thereby
purchased by wire transfer or cashier's check drawn on a United States bank, the
holder of this Warrant shall be entitled to receive a certificate for the number
of shares of Common Stock so purchased. Certificates for shares purchased
hereunder shall be delivered to the holder hereof within three (3) Trading Days
after the date on which this Warrant shall have been exercised as aforesaid.
This Warrant shall be deemed to have been exercised and such certificate or
certificates shall be deemed to have been issued, and Holder or any other person
so designated to be named therein shall be deemed to have become a holder of
record of such shares for all purposes, as of the date the Warrant has been
exercised by payment to the Company of the Exercise Price and all taxes required
to be paid by Holder, if any, pursuant to Section 5 prior to the issuance of
such shares, have been paid. If this Warrant shall have been exercised in part,
the Company shall, at the time of delivery of the certificate or certificates
representing Warrant Shares, deliver to Holder a new Warrant evidencing the
rights of Holder to purchase the unpurchased shares of Common Stock called for
by this Warrant, which new Warrant shall in all other respects be identical with
this Warrant. If, within one year of the date of this Warrant, the Company does
not have an effective Registration Statement to permit the public offering and
resale of the Company's securities which have been issued to Holder under the
Purchase Agreement, then this Warrant may also be exercised by means of a
"cashless exercise" in which the holder shall be entitled to receive a
certificate for the number of shares equal to the quotient obtained by dividing
[(A-B) (X)] by (A), where:

            (A) = the average of the high and low trading prices per share of
            Common Stock on the Trading Day preceding the date of such election;

            (B) =  the Exercise Price of the Warrants; and

            (X) = the number of shares issuable upon exercise of the Warrants in
            accordance with the terms of this Warrant.
<PAGE>

      Notwithstanding anything herein to the contrary, in no event shall the
holder be permitted to exercise this Warrant for shares of Common Stock to the
extent that (x) the number of shares of Common Stock owned by such Holder (other
than shares of Common Stock issuable upon exercise of this Warrant) plus (y) the
number of shares of Common Stock issuable upon exercise of this Warrant, would
be equal to or exceed 9.9% of the number of shares of Common Stock then issued
and outstanding, including shares issuable upon exercise of this Warrant held by
such holder after application of this Section 3(d). As used herein, beneficial
ownership shall be determined in accordance with Section 13(d) of the Exchange
Act. To the extent that the limitation contained in this Section 3(d) applies,
the determination of whether this Warrant is exercisable (in relation to other
securities owned by the holder) and of which a portion of this Warrant is
exercisable shall be in the sole discretion of such holder, and the submission
of a Notice of Exercise shall be deemed to be such holder's determination of
whether this Warrant is exercisable (in relation to other securities owned by
such holder) and of which portion of this Warrant is exercisable, in each case
subject to such aggregate percentage limitation, and the Company shall have no
obligation to verify or confirm the accuracy of such determination. Nothing
contained herein shall be deemed to restrict the right of a holder to exercise
this Warrant into shares of Common Stock at such time as such exercise will not
violate the provisions of this Section 3(d). The provisions of this Section 3(d)
may be waived by the Holder of this Warrant upon, at the election of the Holder,
with 61 days' prior notice to the Company, and the provisions of this Section
3(d) shall continue to apply until such 61st day (or such later date as may be
specified in such notice of waiver). No exercise of this Warrant in violation of
this Section 3(d) but otherwise in accordance with this Warrant shall affect the
status of the Common Stock issued upon such exercise as validly issued,
fully-paid and nonassessable.

            4. No Fractional Shares or Scrip. No fractional shares or scrip
representing fractional shares shall be issued upon the exercise of this
Warrant. As to any fraction of a share which Holder would otherwise be entitled
to purchase upon such exercise, the Company shall pay a cash adjustment in
respect of such final fraction in an amount equal to the such fraction
multiplied by the difference between the closing bid price on the exercise date
Exercise Price.

            5. Charges, Taxes and Expenses. Issuance of certificates for shares
of Common Stock upon the exercise of this Warrant shall be made without charge
to the holder hereof for any issue or transfer tax or other incidental expense
in respect of the issuance of such certificate, all of which taxes and expenses
shall be paid by the Company, and such certificates shall be issued in the name
of the holder of this Warrant or in such name or names as may be directed by the
holder of this Warrant; provided, however, that in the event certificates for
shares of Common Stock are to be issued in a name other than the name of the
holder of this Warrant, this Warrant when surrendered for exercise shall be
accompanied by the Assignment Form attached hereto duly executed by the holder
hereof; and the Company may require, as a condition thereto, the payment of a
sum sufficient to reimburse it for any transfer tax incidental thereto.

            6. Closing of Books. The Company will not close its shareholder
books or records in any manner which prevents the timely exercise of this
Warrant.

            7. Transfer, Division and Combination. (a) Subject to compliance
with any applicable securities laws, transfer of this Warrant and all rights
hereunder, in whole or in part,
<PAGE>

shall be registered on the books of the Company to be maintained for such
purpose, upon surrender of this Warrant at the principal office of the Company,
together with a written assignment of this Warrant substantially in the form
attached hereto duly executed by Holder or its agent or attorney and funds
sufficient to pay any transfer taxes payable upon the making of such transfer.
In the event that the Holder wishes to transfer a portion of this Warrant, the
Holder shall transfer at least 25,000 Warrant Shares to any such transferee.
Upon such surrender and, if required, such payment, the Company shall execute
and deliver a new Warrant or Warrants in the name of the assignee or assignees
and in the denomination or denominations specified in such instrument of
assignment, and shall issue to the assignor a new Warrant evidencing the portion
of this Warrant not so assigned, and this Warrant shall promptly be cancelled. A
Warrant, if properly assigned, may be exercised by a new holder for the purchase
of shares of Common Stock without having a new Warrant issued.

                  (b) This Warrant may be divided or combined with other
Warrants upon presentation hereof at the aforesaid office of the Company,
together with a written notice specifying the names and denominations in which
new Warrants are to be issued, signed by Holder or its agent or attorney.
Subject to compliance with Section 7(a), as to any transfer which may be
involved in such division or combination, the Company shall execute and deliver
a new Warrant or Warrants in exchange for the Warrant or Warrants to be divided
or combined in accordance with such notice.

                  (c) The Company shall prepare, issue and deliver at its own
expense (other than transfer taxes) the new Warrant or Warrants under this
Section 7.

                  (d) The Company agrees to maintain, at its aforesaid office,
books for the registration and the registration of transfer of the Warrants.

            8. No Rights as Shareholder until Exercise. This Warrant does not
entitle the holder hereof to any voting rights or other rights as a shareholder
of the Company prior to the exercise hereof. Upon the surrender of this Warrant
and the payment of the aggregate Exercise Price, the Warrant Shares so purchased
shall be and be deemed to be issued to such holder as the record owner of such
shares as of the close of business on the later of the date of such surrender or
payment.

            9. Loss, Theft, Destruction or Mutilation of Warrant. The Company
covenants that upon receipt by the Company of evidence reasonably satisfactory
to it of the loss, theft, destruction or mutilation of this Warrant certificate
or any stock certificate relating to the Warrant Shares, and in case of loss,
theft or destruction, of indemnity or security reasonably satisfactory to it
(which shall not include the posting of any bond), and upon surrender and
cancellation of such Warrant or stock certificate, if mutilated, the Company
will make and deliver a new Warrant or stock certificate of like tenor and dated
as of such cancellation, in lieu of such Warrant or stock certificate.

            10. Saturdays, Sundays, Holidays, etc. If the last or appointed day
for the taking of any action or the expiration of any right required or granted
herein shall be a Saturday, Sunday or a legal holiday, then such action may be
taken or such right may be exercised on the next succeeding day not a Saturday,
Sunday or legal holiday.
<PAGE>

            11. Adjustments of Exercise Price and Number of Warrant Shares. (a)
Stock Splits, etc. The number and kind of securities purchasable upon the
exercise of this Warrant and the Exercise Price shall be subject to adjustment
from time to time upon the happening of any of the following. In case the
Company shall (i) pay a dividend in shares of Common Stock or make a
distribution in shares of Common Stock to holders of its outstanding Common
Stock, (ii) subdivide its outstanding shares of Common Stock into a greater
number of shares of Common Stock, (iii) combine its outstanding shares of Common
Stock into a smaller number of shares of Common Stock or (iv) issue any shares
of its capital stock in a reclassification of the Common Stock, then the number
of Warrant Shares purchasable upon exercise of this Warrant immediately prior
thereto shall be adjusted so that the holder of this Warrant shall be entitled
to receive the kind and number of Warrant Shares or other securities of the
Company which he would have owned or have been entitled to receive had such
Warrant been exercised in advance thereof. Upon each such adjustment of the kind
and number of Warrant Shares or other securities of the Company which are
purchasable hereunder, the holder of this Warrant shall thereafter be entitled
to purchase the number of Warrant Shares or other securities resulting from such
adjustment at an Exercise Price per Warrant Share or other security obtained by
multiplying the Exercise Price in effect immediately prior to such adjustment by
the number of Warrant Shares purchasable pursuant hereto immediately prior to
such adjustment and dividing by the number of Warrant Shares or other securities
of the Company resulting from such adjustment. An adjustment made pursuant to
this paragraph shall become effective immediately after the effective date of
such event retroactive to the record date, if any, for such event.

                  (b) Reorganization, Reclassification, Merger, Consolidation or
Disposition of Assets. In case the Company shall reorganize its capital,
reclassify its capital stock, consolidate or merge with or into another
corporation (where the Company is not the surviving corporation or where there
is a change in or distribution with respect to the Common Stock of the Company),
or sell, transfer or otherwise dispose of all or substantially all its property,
assets or business to another corporation and, pursuant to the terms of such
reorganization, reclassification, merger, consolidation or disposition of
assets, shares of common stock of the successor or acquiring corporation, or any
cash, shares of stock or other securities or property of any nature whatsoever
(including warrants or other subscription or purchase rights) in addition to or
in lieu of common stock of the successor or acquiring corporation ("Other
Property"), are to be received by or distributed to the holders of Common Stock
of the Company, then Holder shall have the right thereafter to receive, upon
exercise of this Warrant, the number of shares of common stock of the successor
or acquiring corporation or of the Company, if it is the surviving corporation,
and Other Property receivable upon or as a result of such reorganization,
reclassification, merger, consolidation or disposition of assets by a holder of
the number of shares of Common Stock for which this Warrant is exercisable
immediately prior to such event. In case of any such reorganization,
reclassification, merger, consolidation or disposition of assets, the successor
or acquiring corporation (if other than the Company) shall expressly assume the
due and punctual observance and performance of each and every covenant and
condition of this Warrant to be performed and observed by the Company and all
the obligations and liabilities hereunder, subject to such modifications as may
be deemed appropriate (as determined in good faith by resolution of the Board of
Directors of the Company) in order to provide for adjustments of shares of
Common Stock for which this Warrant is exercisable which shall be as nearly
equivalent as practicable to the adjustments provided for in this Section 11.
For purposes of this Section 11, "common stock of the successor or acquiring
corporation" shall include stock of such
<PAGE>

corporation of any class which is not preferred as to dividends or assets over
any other class of stock of such corporation and which is not subject to
redemption and shall also include any evidences of indebtedness, shares of stock
or other securities which are convertible into or exchangeable for any such
stock, either immediately or upon the arrival of a specified date or the
happening of a specified event and any warrants or other rights to subscribe for
or purchase any such stock. The foregoing provisions of this Section 11 shall
similarly apply to successive reorganizations, reclassifications, mergers,
consolidations or disposition of assets.

            12. Voluntary Adjustment by the Company. The Company may at any time
during the term of this Warrant reduce the then current Exercise Price to any
amount and for any period of time deemed appropriate by the Board of Directors
of the Company.

            13. Notice of Adjustment. Whenever the number of Warrant Shares or
number or kind of securities or other property purchasable upon the exercise of
this Warrant or the Exercise Price is adjusted, as herein provided, the Company
shall promptly mail by registered or certified mail, return receipt requested,
to the holder of this Warrant notice of such adjustment or adjustments setting
forth the number of Warrant Shares (and other securities or property)
purchasable upon the exercise of this Warrant and the Exercise Price of such
Warrant Shares (and other securities or property) after such adjustment, setting
forth a brief statement of the facts requiring such adjustment and setting forth
the computation by which such adjustment was made. Such notice, in the absence
of manifest error, shall be conclusive evidence of the correctness of such
adjustment.

            14. Notice of Corporate Action. If at any time:

                  (a) the Company shall take a record of the holders of its
Common Stock for the purpose of entitling them to receive a dividend or other
distribution, or any right to subscribe for or purchase any evidences of its
indebtedness, any shares of stock of any class or any other securities or
property, or to receive any other right, or

                  (b) there shall be any capital reorganization of the Company,
any reclassification or recapitalization of the capital stock of the Company or
any consolidation or merger of the Company with, or any sale, transfer or other
disposition of all or substantially all the property, assets or business of the
Company to, another corporation or,

                  (c) there shall be a voluntary or involuntary dissolution,
liquidation or winding up of the Company;

then, in any one or more of such cases, the Company shall give to Holder (i) at
least 15 days' prior written notice of the date on which a record date shall be
selected for such dividend, distribution or right or for determining rights to
vote in respect of any such reorganization, reclassification, merger,
consolidation, sale, transfer, disposition, liquidation or winding up, and (ii)
in the case of any such reorganization, reclassification, merger, consolidation,
sale, transfer, disposition, dissolution, liquidation or winding up, at least 15
days' prior written notice of the date when the same shall take place. Such
notice in accordance with the foregoing clause also shall specify (i) the date
on which any such record is to be taken for the purpose of such dividend,
distribution or right, the date on which the holders of Common Stock shall be
entitled
<PAGE>

to any such dividend, distribution or right, and the amount and character
thereof, and (ii) the date on which any such reorganization, reclassification,
merger, consolidation, sale, transfer, disposition, dissolution, liquidation or
winding up is to take place and the time, if any such time is to be fixed, as of
which the holders of Common Stock shall be entitled to exchange their shares of
Common Stock for securities or other property deliverable upon such disposition,
dissolution, liquidation or winding up. Each such written notice shall be
sufficiently given if addressed to Holder at the last address of Holder
appearing on the books of the Company and delivered in accordance with Section
16(d).

                  15. Authorized Shares. The Company covenants that during the
period the Warrant is outstanding, it will reserve from its authorized and
unissued Common Stock a sufficient number of shares to provide for the issuance
of the Warrant Shares upon the exercise of any purchase rights under this
Warrant. The Company further covenants that its issuance of this Warrant shall
constitute full authority to its officers who are charged with the duty of
executing stock certificates to execute and issue the necessary certificates for
the Warrant Shares upon the exercise of the purchase rights under this Warrant.
The Company will take all such reasonable action as may be necessary to assure
that such Warrant Shares may be issued as provided herein without violation of
any applicable law or regulation, or of any requirements of the Principal Market
upon which the Common Stock may be listed.

                  The Company shall not by any action, including, without
limitation, amending its certificate of incorporation or through any
reorganization, transfer of assets, consolidation, merger, dissolution, issue or
sale of securities or any other voluntary action, avoid or seek to avoid the
observance or performance of any of the terms of this Warrant, but will at all
times in good faith assist in the carrying out of all such terms and in the
taking of all such actions as may be necessary or appropriate to protect the
rights of Holder against impairment. Without limiting the generality of the
foregoing, the Company will (a) not increase the par value of any shares of
Common Stock receivable upon the exercise of this Warrant above the amount
payable therefor upon such exercise immediately prior to such increase in par
value, (b) take all such action as may be necessary or appropriate in order that
the Company may validly and legally issue fully paid and nonassessable shares of
Common Stock upon the exercise of this Warrant, and (c) use all commercially
reasonable efforts to obtain all such authorizations, exemptions or consents
from any public regulatory body having jurisdiction thereof as may be necessary
to enable the Company to perform its obligations under this Warrant.

                  Upon the request of Holder, the Company will at any time
during the period this Warrant is outstanding acknowledge in writing, in form
reasonably satisfactory to Holder, the continuing validity of this Warrant and
the obligations of the Company hereunder.

                  Before taking any action which would cause an adjustment
reducing the current Exercise Price below the then par value, if any, of the
shares of Common Stock issuable upon exercise of the Warrants, the Company shall
take any corporate action which may be necessary in order that the Company may
validly and legally issue fully paid and non-assessable shares of such Common
Stock at such adjusted Exercise Price.

                  Before taking any action which would result in an adjustment
in the number of shares of Common Stock for which this Warrant is exercisable or
in the Exercise
<PAGE>

Price, the Company shall obtain all such authorizations or exemptions thereof,
or consents thereto, as may be necessary from any public regulatory body or
bodies having jurisdiction thereof.

                  16. Miscellaneous.

                  (a) Jurisdiction. This Warrant shall be binding upon any
successors or assigns of the Company. This Warrant shall constitute a contract
under the laws of New York without regard to its conflict of law principles or
rules, and be subject to arbitration pursuant to the terms set forth in the
Purchase Agreement.

                  (b) Restrictions. The holder hereof acknowledges that the
Warrant Shares acquired upon the exercise of this Warrant, if not registered,
will have restrictions upon resale imposed by state and federal securities laws.

                  (c) Nonwaiver and Expenses. No course of dealing or any delay
or failure to exercise any right hereunder on the part of Holder shall operate
as a waiver of such right or otherwise prejudice Holder's rights, powers or
remedies, notwithstanding all rights hereunder terminate on the Termination
Date. If the Company willfully fails to comply with any material provision of
this Warrant, the Company shall pay to Holder such amounts as shall be
sufficient to cover any costs and expenses including, but not limited to,
reasonable attorneys' fees, including those of appellate proceedings, incurred
by Holder in collecting any amounts due pursuant hereto or in otherwise
enforcing any of its rights, powers or remedies hereunder.

                  (d) Notices. Any notice, request or other document required or
permitted to be given or delivered to the holder hereof by the Company shall be
delivered in accordance with the notice provisions of the Purchase Agreement.

                  (e) Limitation of Liability. No provision hereof, in the
absence of affirmative action by Holder to purchase shares of Common Stock, and
no enumeration herein of the rights or privileges of Holder hereof, shall give
rise to any liability of Holder for the purchase price of any Common Stock or as
a stockholder of the Company, whether such liability is asserted by the Company
or by creditors of the Company.

                  (f) Remedies. Holder, in addition to being entitled to
exercise all rights granted by law, including recovery of damages, will be
entitled to specific performance of its rights under this Warrant. The Company
agrees that monetary damages would not be adequate compensation for any loss
incurred by reason of a breach by it of the provisions of this Warrant and
hereby agrees to waive the defense in any action for specific performance that a
remedy at law would be adequate.

(g) Successors and Assigns. Subject to applicable securities laws, this Warrant
and the rights and obligations evidenced hereby shall inure to the benefit of
and be binding upon the successors of the Company and the successors and
permitted assigns of Holder. The provisions of this Warrant are intended to be
for the benefit of all Holders from time to time of this Warrant and shall be
enforceable by any such Holder or holder of Warrant Shares.
<PAGE>

                  (h) Amendment. This Warrant may be modified or amended or the
provisions hereof waived with the written consent of the Company and the Holder.

                  (i) Severability. Wherever possible, each provision of this
Warrant shall be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Warrant shall be prohibited by or
invalid under applicable law, such provision shall be ineffective to the extent
of such prohibition or invalidity, without invalidating the remainder of such
provisions or the remaining provisions of this Warrant.

                  (j) Headings. The headings used in this Warrant are for the
convenience of reference only and shall not, for any purpose, be deemed a part
of this Warrant.
<PAGE>

            IN WITNESS WHEREOF, the Company has caused this Warrant to be
executed by its officer thereunto duly authorized.


Dated January 19, 2001

                                 Milestone Scientific Inc.


                                 By: /s/ Leonard Osser
                                     ----------------------------------------
                                     Leonard Osser, Chairman & CEO