EXHIBIT 4.2

                                                                 Execution Copy


                         REGISTRATION RIGHTS AGREEMENT

     THIS REGISTRATION RIGHTS AGREEMENT is made and entered into as of
September 11, 2001 by and between Laboratory Corporation of America Holdings, a
Delaware corporation (the "Company"), and Merrill Lynch & Co., Merrill Lynch,
Pierce, Fenner & Smith Incorporated, (the "Initial Purchaser") pursuant to the
Purchase Agreement, dated September 5, 2001 (the "Purchase Agreement"), between
the Company and the Initial Purchaser. In order to induce the Initial Purchaser
to enter into the Purchase Agreement, the Company has agreed to provide the
registration rights set forth in this Agreement. The execution of this
Agreement is a condition to the closing under the Purchase Agreement.

     The Company agrees with the Initial Purchaser, (i) for its benefit as
Initial Purchaser and (ii) for the benefit of the beneficial owners (including
the Initial Purchaser) from time to time of the LYONs (as defined herein) and
the beneficial owners from time to time of the Underlying Common Stock (as
defined herein) issued upon conversion of the LYONs (each of the foregoing a
"Holder" and together the "Holders"), as follows:

     Section 1. Definitions. Capitalized terms used herein without definition
shall have their respective meanings set forth in the Purchase Agreement. As
used in this Agreement, the following terms shall have the following meanings:

     "Affiliate" means, with respect to any specified person, an "affiliate,"
as defined in Rule 144, of such person.

     "Amendment Effectiveness Deadline Date" has the meaning specified in
Section 2(d) hereof.

     "Applicable Conversion Price" means, as of any date, the Applicable
Principal Amount per $1,000 principal amount at maturity of LYONs as of such
date of determination divided by the Conversion Rate in effect as of such date
of determination or, if no LYONs are then outstanding, the Conversion Rate that
would be in effect were LYONs then outstanding.

     "Applicable Principal Amount" with respect to each $1,000 principal amount
at maturity of LYONs means, as of any date, the sum of the initial issue price
of such LYONs ($671.65) plus accrued original issue discount, and contingent
additional principal (and accrued original issued discount thereon), if any,
with respect to such LYON through such date of determination or, if no LYONs
are then outstanding, such sum calculated as if such LYONs were then
outstanding.

     "Business Day" means each Monday, Tuesday, Wednesday, Thursday and Friday
that is not a day on which banking institutions in The City of New York are
authorized or obligated by law or executive order to close.

     "Common Stock" means the shares of Common Stock, $0.10 par value, of the
Company and any other shares of common stock as may constitute "Common Stock"
for purposes of the Indenture, including the Underlying Common Stock.


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     "Conversion Rate" has the meaning assigned to that term in the Indenture.

     "Damages Accrual Period" has the meaning specified in Section 2(e) hereof.

     "Damages Payment Date" means each September 11 and March 11 in the case of
LYONs and the Underlying Common Stock.

     "Deferral Notice" has the meaning specified in Section 3(i) hereof.

     "Deferral Period" has the meaning specified in Section 3(i) hereof.

     "Effectiveness Deadline Date" has the meaning specified in Section 2(a)
hereof.

     "Effectiveness Period" means the period of two years from (1) the later of
(a) the Issue Date or (b) the last date of original issuance of the LYONs or
(2) such shorter period ending on the date that all Registrable Securities have
ceased to be Registrable Securities.

     "Event" has the meaning specified in Section 2(e) hereof.

     "Event Termination Date" has the meaning specified in Section 2(e) hereof.

     "Event Date" has the meaning specified in Section 2(e) hereof.

     "Exchange Act" means the Securities Exchange Act of 1934, as amended, and
the rules and regulations of the SEC promulgated thereunder.

     "Filing Deadline Date" has the meaning specified in Section 2(a) hereof.

     "Holder" has the meaning specified in the second paragraph of this
Agreement.

     "Indenture" means the Indenture dated as of the date hereof between the
Company and The Bank of New York, as trustee, pursuant to which the LYONs are
being issued.

     "Initial Purchaser" means Merrill Lynch & Co., Merrill Lynch, Pierce,
Fenner & Smith Incorporated.

     "Initial Shelf Registration Statement" has the meaning specified in
Section 2(a) hereof.

     "Issue Date" means September 11, 2001.

     "Liquidated Damages Amount" has the meaning specified in Section 2(e)
hereof.

     "Losses" has the meaning specified in Section 6 hereof.

     "LYONs" means the Liquid Yield Option(TM) Notes due 2021 of the Company to
be purchased pursuant to the Purchase Agreement.

     "Material Event" has the meaning specified in Section 3(i) hereof.


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     "Notice and Questionnaire" means a written notice delivered to the Company
containing substantially the information called for by the Selling
Securityholder Notice and Questionnaire attached as Annex A to the Offering
Memorandum of the Company dated September 5, 2001 relating to the LYONs.

     "Notice Holder" means, on any date, any Holder that has delivered a Notice
and Questionnaire to the Company on or prior to such date.

     "Prospectus" means the prospectus included in any Registration Statement,
as amended or supplemented by any amendment or prospectus supplement, including
post-effective amendments, and all materials incorporated by reference or
explicitly deemed to be incorporated by reference in such Prospectus.

     "Purchase Agreement" has the meaning specified in the first paragraph of
this Agreement.

     "Record Holder" means, with respect to any Damages Payment Date relating
to any LYON or any share of Underlying Common Stock as to which any Liquidated
Damages Amount has accrued, the registered holder of such LYON or any share of
Underlying Common Stock, as the case may be, 15 days prior to such Damages
Payment Date.

     "Registrable Securities" means the LYONs and the Underlying Common Stock
until such securities have been converted or exchanged, and, at all times
subsequent to any such conversion or exchange, any securities into or for which
such securities have been converted or exchanged, and any security issued with
respect thereto upon any stock dividend, split or similar event until, in the
case of any such security, the earliest of (i) its effective registration under
the Securities Act and resale in accordance with the Registration Statement
covering it, (ii) expiration of the holding period that would be applicable
thereto under Rule 144(k) were it not held by an Affiliate of the Company or
(iii) its sale to the public pursuant to Rule 144.

     "Registration Expenses" has the meaning specified in Section 5 hereof.

     "Registration Statement" means any registration statement of the Company
that covers any of the Registrable Securities pursuant to the provisions of
this Agreement, including the Prospectus, amendments and supplements to such
registration statement, including post-effective amendments, all exhibits, and
all materials incorporated by reference or explicitly deemed to be incorporated
by reference in such registration statement.

     "Restricted Securities" has the meaning assigned to that term in Rule 144.

     "Rule 144" means Rule 144 under the Securities Act, as such Rule may be
amended from time to time, or any similar rule or regulation hereafter adopted
by the SEC.

     "Rule 144A" means Rule 144A under the Securities Act, as such Rule may be
amended from time to time, or any similar rule or regulation hereafter adopted
by the SEC.

     "SEC" means the U.S. Securities and Exchange Commission and any successor
agency.


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     "Securities Act" means the Securities Act of 1933, as amended, and the
rules and regulations promulgated by the SEC thereunder.

     "Shelf Registration Statement" has the meaning specified in Section 2(a)
hereof.

     "Subsequent Shelf Registration Statement" has the meaning specified in
Section 2(b) hereof.

     "TIA" means the Trust Indenture Act of 1939, as amended.

     "Trustee" means The Bank of New York (or any successor entity), the
Trustee under the Indenture.

     "Underlying Common Stock" The Common Stock into which the LYONs are
convertible or issued upon any such conversion.

     Section 2. Shelf Registration. (a) The Company shall prepare and file or
cause to be prepared and filed with the SEC, as soon as practicable but in any
event by the date (the "Filing Deadline Date") ninety (90) days after the Issue
Date, a Registration Statement for an offering to be made on a delayed or
continuous basis pursuant to Rule 415 of the Securities Act (a "Shelf
Registration Statement") registering the resale from time to time by Holders
thereof of all of the Registrable Securities (the "Initial Shelf Registration
Statement"). The Initial Shelf Registration Statement shall be on Form S-3 or
another appropriate form permitting registration of such Registrable Securities
for resale by such Holders in accordance with the methods of distribution
reasonably elected by the Holders and set forth in the Initial Shelf
Registration Statement, provided that in no event will such method(s) of
distribution take the form of an underwritten offering of the Registrable
Securities without the prior agreement of the Company. The Company shall use
reasonable efforts to cause the Initial Shelf Registration Statement to be
declared effective under the Securities Act as promptly as is practicable but
in any event by the date (the "Effectiveness Deadline Date") that is one
hundred and eighty (180) days after the Issue Date, and to keep the Initial
Shelf Registration Statement (or any Subsequent Shelf Registration Statement)
continuously effective under the Securities Act until the expiration of the
Effectiveness Period; provided, however, that no Holder shall be entitled to
have the Registrable Securities held by it covered by such Shelf Registration
Statement unless such Holder shall have provided a Notice and Questionnaire in
accordance with Section 2(d) and is in compliance with Section 4. None of the
Company's security holders (other than the Holders of Registrable Securities)
shall have the right to include any of the Company's securities in the Shelf
Registration Statement.

     (b) If the Initial Shelf Registration Statement or any Subsequent Shelf
Registration Statement ceases to be effective for any reason at any time during
the Effectiveness Period (other than as permitted in Section 3(i) hereof or
because all Registrable Securities registered thereunder shall have been resold
pursuant thereto or shall have otherwise ceased to be Registrable Securities),
the Company shall use all reasonable efforts to obtain the prompt withdrawal of
any order suspending the effectiveness thereof, and in any event shall within
thirty (30) days of such cessation of effectiveness amend the Shelf
Registration Statement in a manner reasonably expected to obtain the withdrawal
of the order suspending the effectiveness thereof,


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or file an additional Shelf Registration Statement covering all of the
securities that as of the date of such filing are Registrable Securities (a
"Subsequent Shelf Registration Statement"). If a Subsequent Shelf Registration
Statement is filed, the Company shall use all reasonable efforts to cause the
Subsequent Shelf Registration Statement to become effective as promptly as is
practicable after such filing and to keep such Subsequent Shelf Registration
Statement continuously effective (subject to Section 3(i) hereof) until the end
of the Effectiveness Period.

     (c) The Company shall supplement and amend the Shelf Registration
Statement if required by the rules, regulations or instructions applicable to
the registration form used by the Company for such Shelf Registration
Statement, if required by the Securities Act or, to the extent to which the
Company does not reasonably object, as reasonably requested by the Initial
Purchaser or by the Trustee on behalf of the registered Holders.

     (d) Each Holder of Registrable Securities agrees that if such Holder
wishes to sell Registrable Securities pursuant to a Shelf Registration
Statement and related Prospectus (whether or not such Holder was a Notice
Holder at the time the Registration Statement was declared effective), it will
do so only in accordance with this Section 2(d) and Section 3(i). Each Holder
of Registrable Securities wishing to sell Registrable Securities pursuant to a
Shelf Registration Statement and related Prospectus agrees to deliver a Notice
and Questionnaire to the Company at least three (3) Business Days prior to any
intended distribution of Registrable Securities under the Shelf Registration
Statement. From and after the date the Initial Shelf Registration Statement is
declared effective, the Company shall, as promptly as is reasonably practicable
after the date a Notice and Questionnaire is delivered, and in any event within
five (5) Business Days after such date, (i) if required by applicable law, file
with the SEC a post-effective amendment to the Shelf Registration Statement or
prepare and, if required by applicable law, file a supplement to the related
Prospectus or a supplement or amendment to any document incorporated therein by
reference or file any other required document so that the Holder delivering
such Notice and Questionnaire is named as a selling security holder in the
Shelf Registration Statement and the related Prospectus in such a manner as to
permit such Holder to deliver such Prospectus to purchasers of the Registrable
Securities in accordance with applicable law and, if the Company shall file a
post-effective amendment to the Shelf Registration Statement, use reasonable
efforts to cause such post-effective amendment to be declared effective under
the Securities Act as promptly as is practicable, but in any event by the date
(the "Amendment Effectiveness Deadline Date") that is forty-five (45) days
after the date such post-effective amendment is required by this clause to be
filed; (ii) provide such Holder copies of any documents filed pursuant to
Section 2(d)(i); and (iii) notify such Holder as promptly as reasonably
practicable after the effectiveness under the Securities Act of any
post-effective amendment filed pursuant to Section 2(d)(i); provided that if
such Notice and Questionnaire is delivered during a Deferral Period, the
Company shall so inform the Holder delivering such Notice and Questionnaire and
shall take the actions set forth in clauses (i), (ii) and (iii) above upon
expiration of the Deferral Period in accordance with Section 3(i).
Notwithstanding anything contained herein to the contrary, the Company shall be
under no obligation to name any Holder that is not a Notice Holder as a selling
security holder in any Registration Statement or related Prospectus.

     (e) The parties hereto agree that the Holders of Registrable Securities
will suffer damages, and that it would not be feasible to ascertain the extent
of such damages with


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precision, if (i) the Initial Shelf Registration Statement has not been filed
on or prior to the Filing Deadline Date, (ii) the Initial Shelf Registration
Statement has not been declared effective under the Securities Act on or prior
to the Effectiveness Deadline Date, (iii) the Company has failed to perform its
obligations set forth in Section 2(d) hereof within the time period required
therein, (iv) the aggregate duration of Deferral Periods in any period exceeds
the number of days permitted in respect of such period pursuant to Section 3(i)
hereof or (v) the number of Deferral Periods in any period exceeds the number
permitted in respect of such period pursuant to Section 3(i) (each of the
events of a type described in any of the foregoing clauses (i) through (v) are
individually referred to herein as an "Event," and the Filing Deadline Date in
the case of clause (i), the Effectiveness Deadline Date in the case of clause
(ii), the date by which the Company is required to perform its obligations set
forth in Section 2(d) in the case of clause (iii) (including the filing of any
post-effective amendment prior to the Amendment Effectiveness Deadline Date),
the date on which the aggregate duration of Deferral Periods in any period
exceeds the number of days permitted by Section 3(i) hereof in the case of
clause (iv), and the date of the commencement of a Deferral Period that causes
the limit on the number of Deferral Periods in any period under Section 3(i)
hereof to be exceeded in the case of clause (v), being referred to herein as an
"Event Date"). Events shall be deemed to continue until the "Event Termination
Date," which shall be the following dates with respect to the respective types
of Events: the date the Initial Shelf Registration Statement is filed in the
case of an Event of the type described in clause (i), the date the Initial
Shelf Registration Statement is declared effective under the Securities Act in
the case of an Event of the type described in clause (ii), the date the Company
performs its obligations set forth in Section 2(d) in the case of an Event of
the type described in clause (iii) (including, without limitation, the date the
relevant post-effective amendment to the Shelf Registration Statement is
declared effective under the Securities Act), termination of the Deferral
Period that caused the limit on the aggregate duration of Deferral Periods in a
period set forth in Section 3(i) to be exceeded in the case of the commencement
of an Event of the type described in clause (iv), and termination of the
Deferral Period the commencement of which caused the number of Deferral Periods
in a period permitted by Section 3(i) to be exceeded in the case of an Event of
the type described in clause (v).

     Accordingly, commencing on (and including) any Event Date and ending on
(but excluding) the next date on which there are no Events that have occurred
and are continuing (a "Damages Accrual Period"), the Company agrees to pay, as
liquidated damages and not as a penalty, an amount (the "Liquidated Damages
Amount"), payable on the Damages Payment Dates to Record Holders of then
outstanding LYONs that are Registrable Securities and of then outstanding
shares of Underlying Common Stock issued upon conversion of LYONs that are
Registrable Securities, as the case may be, accruing, for each portion of such
Damages Accrual Period beginning on and including a Damages Payment Date (or,
in respect of the first time that the Liquidation Damages Amount is to be paid
to Holders on a Damages Payment Date as a result of the occurrence of any
particular Event, from the Event Date) and ending on but excluding the first to
occur of (A) the date of the end of the Damages Accrual Period or (B) the Next
Damages Payment Date, at a rate per annum equal to one-quarter of one percent
(0.25%) for the first 90-day period from the Event Date, and thereafter at a
rate per annum equal to one-half of one percent (0.5%) of the aggregate
Applicable Principal Amount of such LYONs, or, in the case of LYONs that have
been converted into or exchanged for Underlying Common Stock, the Applicable
Conversion Price of such shares of Underlying Common Stock, as the case may be,
in each case determined as of the Business Day immediately preceding the next
Damages


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Payment Date; provided, that any Liquidated Damages Amount accrued with
respect to any LYON or portion thereof called for redemption on a redemption
date or converted into Underlying Common Stock on a conversion date prior to
the Damages Payment Date, shall, in any such event, be paid instead to the
Holder who submitted such LYON or portion thereof for redemption or conversion
on the applicable redemption date or conversion date, as the case may be, on
such date (or promptly following the conversion date, in the case of
conversion). Notwithstanding the foregoing, no Liquidated Damages Amounts shall
accrue as to any Registrable Security from and after the earlier of (x) the
date such security is no longer a Registrable Security and (y) expiration of
the Effectiveness Period. The rate of accrual of the Liquidated Damages Amount
with respect to any period shall not exceed the rate provided for in this
paragraph notwithstanding the occurrence of multiple concurrent Events.
Following the cure of all Events requiring the payment by the Company of
Liquidated Damages Amounts to the Holders of Registrable Securities pursuant to
this Section, the accrual of Liquidated Damages Amounts will cease (without in
any way limiting the effect of any subsequent Event requiring the payment of
Liquidated Damages Amount by the Company).

     The Trustee shall be entitled, on behalf of Holders of LYONs or Underlying
Common Stock, to seek any available remedy for the enforcement of this
Agreement, including for the payment of any Liquidated Damages Amount.
Notwithstanding the foregoing, the parties agree that the sole monetary damages
payable for a violation of the terms of this Agreement with respect to which
Liquidated Damages are expressly provided shall be such Liquidated Damages.
Nothing shall preclude a Notice Holder or Holder of Registrable Securities from
pursuing or obtaining specific performance or other equitable relief with
respect to this Agreement.

     All of the Company's obligations set forth in this Section 2(e) that are
outstanding with respect to any Registrable Security at the time such security
ceases to be a Registrable Security shall survive until such time as all such
obligations with respect to such security have been satisfied in full
(notwithstanding termination of this Agreement pursuant to Section 8(k)).

     The parties hereto agree that the liquidated damages provided for in this
Section 2(e) constitute a reasonable estimate of the damages that may be
incurred by Holders of Registrable Securities by reason of the failure of the
Shelf Registration Statement to be filed or declared effective or available for
effecting resales of Registrable Securities in accordance with the provisions
hereof.

     Section 3. Registration Procedures. In connection with the registration
obligations of the Company under Section 2 hereof, the Company shall:

          (a) Before filing any Registration Statement or Prospectus or any
     amendments or supplements thereto with the SEC, furnish to the Initial
     Purchaser copies of all such documents proposed to be filed and use
     reasonable efforts to reflect in each such document when so filed with the
     SEC such comments as the Initial Purchaser reasonably shall propose within
     three (3) Business Days of the delivery of such copies to the Initial
     Purchaser.

          (b) Prepare and file with the SEC such amendments and post-effective
     amendments to each Registration Statement as may be necessary to keep such


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     Registration Statement continuously effective for the applicable period
     specified in Section 2(a); cause the related Prospectus to be supplemented
     by any required Prospectus supplement, and as so supplemented to be filed
     pursuant to Rule 424 (or any similar provisions then in force) under the
     Securities Act; and use all reasonable efforts to comply with the
     provisions of the Securities Act applicable to it with respect to the
     disposition of all securities covered by such Registration Statement
     during the Effectiveness Period in accordance with the intended methods of
     disposition by the sellers thereof set forth in such Registration
     Statement as so amended or such Prospectus as so supplemented.

          (c) As promptly as practicable give notice to the Notice Holders and
     the Initial Purchaser (i) when any Prospectus, Prospectus supplement,
     Registration Statement or post-effective amendment to a Registration
     Statement has been filed with the SEC and, with respect to a Registration
     Statement or any post-effective amendment, when the same has been declared
     effective, (ii) of any request, following the effectiveness of the Initial
     Shelf Registration Statement under the Securities Act, by the SEC or any
     other federal or state governmental authority for amendments or
     supplements to any Registration Statement or related Prospectus or for
     additional information, (iii) of the issuance by the SEC or any other
     federal or state governmental authority of any stop order suspending the
     effectiveness of any Registration Statement or the initiation or
     threatening of any proceedings for that purpose, (iv) of the receipt by
     the Company of any notification with respect to the suspension of the
     qualification or exemption from qualification of any of the Registrable
     Securities for sale in any jurisdiction or the initiation or threatening
     of any proceeding for such purpose, (v) of the occurrence of (but not the
     nature of or details concerning) a Material Event (provided, however, that
     no notice by the Company shall be required pursuant to this clause (v) in
     the event that the Company either promptly files a Prospectus supplement
     to update the Prospectus or a Form 8-K or other appropriate Exchange Act
     report that is incorporated by reference into the Registration Statement,
     which, in either case, contains the requisite information with respect to
     such Material Event that results in such Registration Statement no longer
     containing any untrue statement of material fact or omitting to state a
     material fact necessary to make the statements contained therein not
     misleading) and (vi) of the determination by the Company that a
     post-effective amendment to a Registration Statement will be filed with
     the SEC, which notice may, at the discretion of the Company (or as
     required pursuant to Section 3(i)), state that it constitutes a Deferral
     Notice, in which event the provisions of Section 3(i) shall apply.

          (d) Use all reasonable efforts to obtain the withdrawal of any order
     suspending the effectiveness of a Registration Statement or the lifting of
     any suspension of the qualification (or exemption from qualification) of
     any of the Registrable Securities for sale in any jurisdiction in which
     they have been qualified for sale, in either case at the earliest possible
     moment.

          (e) If reasonably requested by the Initial Purchaser or any Notice
     Holder, promptly as reasonably practicable incorporate in a Prospectus
     supplement or post-effective amendment to a Registration Statement such
     information as the Initial Purchaser or such Notice Holder shall, on the
     basis of an opinion of nationally-recognized counsel


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     experienced in such matters, determine to be required to be included
     therein by applicable law and make any required filings of such Prospectus
     supplement or such post-effective amendment; provided, that the Company
     shall not be required to take any actions under this Section 3(e) that are
     not, in the reasonable opinion of counsel for the Company, in compliance
     with applicable law.

          (f) As promptly as reasonably practicable furnish to each Notice
     Holder and the Initial Purchaser, upon their request and without charge,
     at least one (1) conformed copy of the Registration Statement and any
     amendment thereto, including financial statements but excluding schedules,
     all documents incorporated or deemed to be incorporated therein by
     reference and all exhibits (unless requested in writing to the Company by
     such Notice Holder or the Initial Purchaser, as the case may be).

          (g) During the Effectiveness Period, deliver to each Notice Holder in
     connection with any sale of Registrable Securities pursuant to a
     Registration Statement, without charge, as many copies of the Prospectus
     or Prospectuses relating to such Registrable Securities (including each
     preliminary prospectus) and any amendment or supplement thereto as such
     Notice Holder may reasonably request; and the Company hereby consents
     (except during such periods that a Deferral Notice is outstanding and has
     not been revoked) to the use of such Prospectus or each amendment or
     supplement thereto by each Notice Holder in connection with any offering
     and sale of the Registrable Securities covered by such Prospectus or any
     amendment or supplement thereto in the manner set forth therein.

          (h) Prior to any public offering of the Registrable Securities
     pursuant to the Shelf Registration Statement, use all reasonable efforts
     to register or qualify or cooperate with the Notice Holders in connection
     with the registration or qualification (or exemption from such
     registration or qualification) of such Registrable Securities for offer
     and sale under the securities or Blue Sky laws of such jurisdictions
     within the United States as any Notice Holder reasonably requests in
     writing (which request may be included in the Notice and Questionnaire),
     it being agreed that no such registration or qualification will be
     required unless so requested; prior to any public offering of the
     Registrable Securities pursuant to the Shelf Registration Statement, use
     all reasonable efforts to keep each such registration or qualification (or
     exemption therefrom) effective during the Effectiveness Period in
     connection with such Notice Holder's offer and sale of Registrable
     Securities pursuant to such registration or qualification (or exemption
     therefrom) and do any and all other acts or things necessary or advisable
     to enable the disposition in such jurisdictions of such Registrable
     Securities in the manner set forth in the relevant Registration Statement
     and the related Prospectus; provided, that the Company will not be
     required to (i) qualify as a foreign corporation or as a dealer in
     securities in any jurisdiction where it would not otherwise be required to
     qualify but for this Agreement or (ii) take any action that would subject
     it to general service of process in suits or to taxation in any such
     jurisdiction where it is not then so subject.

          (i) Upon (A) the issuance by the SEC of a stop order suspending the
     effectiveness of the Shelf Registration Statement or the initiation of
     proceedings with respect to the Shelf Registration Statement under Section
     8(d) or 8(e) of the Securities


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     Act, (B) the occurrence of any event or the existence of any fact (a
     "Material Event") as a result of which any Registration Statement shall
     contain any untrue statement of a material fact or omit to state any
     material fact required to be stated therein or necessary to make the
     statements therein not misleading, or any Prospectus shall contain any
     untrue statement of a material fact or omit to state any material fact
     required to be stated therein or necessary to make the statements therein,
     in the light of the circumstances under which they were made, not
     misleading, or (C) the occurrence or existence of any pending corporate
     development that, in the discretion of the Company, makes it appropriate
     to suspend the availability of the Shelf Registration Statement and the
     related Prospectus, (i) in the case of clause (B) above, subject to the
     next sentence, as promptly as practicable prepare and file a
     post-effective amendment to such Registration Statement or a supplement to
     the related Prospectus or any document incorporated therein by reference
     or file any other required document that would be incorporated by
     reference into such Registration Statement and Prospectus so that such
     Registration Statement does not contain any untrue statement of a material
     fact or omit to state any material fact required to be stated therein or
     necessary to make the statements therein not misleading, and such
     Prospectus does not contain any untrue statement of a material fact or
     omit to state any material fact required to be stated therein or necessary
     to make the statements therein, in the light of the circumstances under
     which they were made, not misleading, as thereafter delivered to the
     purchasers of the Registrable Securities being sold thereunder, and, in
     the case of a post-effective amendment to a Registration Statement,
     subject to the next sentence, use all reasonable efforts to cause it to be
     declared effective as promptly as is reasonably practicable, and (ii) give
     notice to the Notice Holders that the availability of the Shelf
     Registration Statement is suspended (a "Deferral Notice") and, upon
     receipt of any Deferral Notice, each Notice Holder agrees not to sell any
     Registrable Securities pursuant to the Registration Statement until such
     Notice Holder's receipt of copies of the supplemented or amended
     Prospectus provided for in clause (i) above, or until it is advised in
     writing by the Company that the Prospectus may be used, and has received
     copies of any additional or supplemental filings that are incorporated or
     deemed incorporated by reference in such Prospectus. The Company will use
     all reasonable efforts to ensure that the use of the Prospectus may be
     resumed (x) in the case of clause (A) above, as promptly as is
     practicable, (y) in the case of clause (B) above, as soon as, in the sole
     judgment of the Company, public disclosure of such Material Event would
     not be prejudicial to or contrary to the interests of the Company or, if
     necessary to avoid unreasonable burden or expense, as soon as reasonably
     practicable thereafter and (z) in the case of clause (C) above, as soon
     as, in the discretion of the Company, such suspension is no longer
     appropriate. The period during which the availability of the Registration
     Statement and any Prospectus is suspended (the "Deferral Period") shall,
     without the Company incurring any obligation to pay liquidated damages
     pursuant to Section 2(e), not exceed forty-five (45) days in any three (3)
     month period or ninety (90) days in any twelve (12) month period.

          (j) If reasonably requested in writing in connection with a
     disposition of Registrable Securities pursuant to a Registration
     Statement, make reasonably available for inspection during normal business
     hours by a representative for the Notice Holders of such Registrable
     Securities and any broker-dealers, attorneys and accountants retained by
     such Notice Holders, all relevant financial and other records, pertinent
     corporate


                                      10

<PAGE>


     documents and properties of the Company and its subsidiaries,
     and cause the appropriate executive officers, directors and designated
     employees of the Company and its subsidiaries to make reasonably available
     for inspection during normal business hours all relevant information
     reasonably requested by such representative for the Notice Holders or any
     such broker-dealers, attorneys or accountants in connection with such
     disposition, in each case as is customary for similar "due diligence"
     examinations; provided, however, that such persons shall first agree in
     writing with the Company that any information that is reasonably and in
     good faith designated by the Company in writing as confidential at the
     time of delivery of such information shall be kept confidential by such
     persons and shall be used solely for the purposes of exercising rights
     under this Agreement, unless (i) disclosure of such information is
     required by court or administrative order or is necessary to respond to
     inquiries of regulatory authorities, (ii) disclosure of such information
     is required by law (including any disclosure requirements pursuant to
     federal securities laws in connection with the filing of any Registration
     Statement or the use of any Prospectus referred to in this Agreement),
     (iii) such information becomes generally available to the public other
     than as a result of a disclosure or failure to safeguard by any such
     person or (iv) such information becomes available to any such person from
     a source other than the Company and such source is not bound by a
     confidentiality agreement; and provided further, that the foregoing
     inspection and information gathering shall, to the greatest extent
     possible, be coordinated on behalf of all the Notice Holders and the other
     parties entitled thereto by the counsel referred to in Section 5.

          (k) Comply with all applicable rules and regulations of the SEC and
     make generally available to its securityholders earning statements (which
     need not be audited) satisfying the provisions of Section 11(a) of the
     Securities Act and Rule 158 thereunder (or any similar rule promulgated
     under the Securities Act) no later than 45 days after the end of any
     3-month period (or 120 days after the end of any 12-month period if such
     period is a fiscal year) commencing on the first day of the first fiscal
     quarter of the Company commencing after the effective date of a
     Registration Statement, which statements shall cover said periods.

          (l) Cooperate with each Notice Holder to facilitate the timely
     preparation and delivery of certificates representing Registrable
     Securities sold pursuant to a Registration Statement, and cause such
     Registrable Securities to be in such denominations as are permitted by the
     Indenture and registered in such names as such Notice Holder may request
     in writing at least one Business Day prior to any sale of such Registrable
     Securities.

          (m) Provide a CUSIP number for all Registrable Securities covered by
     each Registration Statement not later than the effective date of such
     Registration Statement and provide the Trustee for the LYONs and the
     transfer agent for the Common Stock with printed certificates for the
     Registrable Securities that are in a form eligible for deposit with The
     Depository Trust Company.

          (n) Make a reasonable effort to provide such information as is
     required for any filings required to be made with the National Association
     of Securities Dealers, Inc., if any.


                                      11

<PAGE>


          (o) Upon (i) the filing of the Initial Shelf Registration Statement
     and (ii) the effectiveness of the Initial Shelf Registration Statement,
     announce the same, in each case by release to Reuters Economic Services
     and Bloomberg Business News.

          (p) If the Company agrees to the underwritten offering of Registrable
     Securities pursuant to Section 2(a) hereof, enter into such customary
     agreements and take all such other reasonable necessary actions in
     connection therewith (including those reasonably requested by the holders
     of a majority of the Registrable Securities being sold) in order to
     expedite or facilitate disposition of such Registrable Securities.

          (q) Cause the Indenture to be qualified under the TIA not later than
     the effective date of any Registration Statement; and in connection
     therewith, cooperate with the Trustee to effect such changes to the
     Indenture as may be required for the Indenture to be so qualified in
     accordance with the terms of the TIA and execute, and use all reasonable
     efforts to cause the Trustee to execute, all documents as may be required
     to effect such changes, and all other forms and documents required to be
     filed with the SEC to enable the Indenture to be so qualified in a timely
     manner.

     Section 4. Holder's Obligations. Each Holder agrees, by acquisition of the
Registrable Securities, that no Holder of Registrable Securities shall be
entitled to sell any of such Registrable Securities pursuant to a Registration
Statement or to receive a Prospectus relating thereto, unless such Holder has
furnished the Company with a Notice and Questionnaire as required pursuant to
Section 2(d) hereof (including the information required to be included in such
Notice and Questionnaire) and the information set forth in the next sentence.
Each Notice Holder agrees promptly to furnish to the Company all information
required to be disclosed in order to make the information previously furnished
to the Company by such Notice Holder not misleading and any other information
regarding such Notice Holder and the distribution of such Registrable
Securities as may be required to be disclosed in the Registration Statement
under applicable law or pursuant to SEC comment or as may otherwise be required
by the Company to comply with applicable laws or regulations.

     Section 5. Registration Expenses. The Company shall bear all fees and
expenses incurred in connection with the performance by the Company of its
obligations under Sections 2 and 3 of this Agreement whether or not any of the
Registration Statements are declared effective. Such fees and expenses shall
include, without limitation, (i) all registration and filing fees (including,
without limitation, fees and expenses (x) with respect to filings required to
be made with the National Association of Securities Dealers, Inc., if any, and
(y) of compliance with federal and state securities or Blue Sky laws
(including, without limitation, reasonable fees and disbursements of the
counsel specified in the next sentence in connection with Blue Sky
qualifications of the Registrable Securities under the laws of such
jurisdictions as the Notice Holders of a majority of the Registrable Securities
being sold pursuant to a Registration Statement may designate), (ii) printing
expenses (including, without limitation, expenses of printing certificates for
Registrable Securities in a form eligible for deposit with The Depository Trust
Company), (iii) duplication expenses relating to copies of any Registration
Statement or Prospectus delivered to any Holders hereunder, (iv) fees and
disbursements of counsel for the Company in connection with the Shelf
Registration Statement, and (v) reasonable fees and disbursements of the
Trustee and its counsel and of the registrar and transfer agent for the


                                      12

<PAGE>


Common Stock. In addition, the Company shall bear or reimburse the Notice
Holders for the reasonable fees and disbursements of one firm of legal counsel
for the Holders, which shall initially be Shearman & Sterling, but which may,
upon the written consent of the Initial Purchaser (which shall not be
unreasonably withheld), be another nationally recognized law firm experienced
in securities law matters designated by the Company. In addition, the Company
shall pay the internal expenses of the Company (including, without limitation,
all salaries and expenses of officers and employees performing legal or
accounting duties), the expense of any annual audit, the fees and expenses
incurred in connection with the listing of the Registrable Securities on any
securities exchange on which similar securities of the Company are then listed
and the fees and expenses of any person, including special experts, retained by
the Company.

     Section 6. Indemnification; Contribution. (a) The Company agrees to
indemnify and hold harmless the Initial Purchaser and each holder of
Registrable Securities and each person, if any, who controls the Initial
Purchaser or any holder of Registrable Securities within the meaning of either
Section 15 of the Securities Act or Section 20 of the Exchange Act, as follows:

          (i) against any and all loss, liability, claim, damage and expense
     whatsoever, as incurred, arising out of any untrue statement or alleged
     untrue statement of a material fact contained in the Registration
     Statement (or any amendment thereto), or the omission or alleged omission
     therefrom of a material fact necessary in order to make the statements
     therein, in light of the circumstances under which they were made, not
     misleading or arising out of any untrue statement or alleged untrue
     statement of a material fact included in any preliminary prospectus or the
     Prospectus (or any amendment or supplement thereto), or the omission or
     alleged omission therefrom of a material fact necessary in order to make
     the statements therein, in the light of the circumstances under which they
     were made, not misleading;

          (ii) against any and all loss, liability, claim, damage and expense
     whatsoever, as incurred, to the extent of the aggregate amount paid in
     settlement of any litigation, or any investigation or proceeding by any
     governmental agency or body, commenced or threatened, or of any claim
     whatsoever based upon any such untrue statement or omission, or any such
     alleged untrue statement or omission, provided that (subject to Section
     6(d) below) any such settlement is effected with the prior written consent
     of the Company; and

          (iii) against any and all expense whatsoever, as incurred (including
     the fees and disbursements of counsel), reasonably incurred in
     investigating, preparing or defending against any litigation, or any
     investigation or proceeding by any governmental agency or body, commenced
     or threatened, or any claim whatsoever based upon any such untrue
     statement or omission, or any such alleged untrue statement or omission,
     to the extent that any such expense is not paid under (i) or (ii) above;

provided, however, that this indemnity shall not apply to any loss, liability,
claim, damage or expense to the extent arising out of any untrue statement or
omission or alleged untrue statement or omission made in reliance upon and in
conformity with written information furnished to the Company by the Initial
Purchaser or Notice Holder expressly for use in the Registration


                                      13

<PAGE>


Statement (or any amendment thereto), or any preliminary prospectus or the
Prospectus (or any amendment or supplement thereto); provided, further, that
this indemnity agreement shall not apply to any loss, liability, claim, damage
or expense (1) arising from an offer or sale of Registrable Securities
occurring during a Deferral Period, if a Deferral Notice was given to such
Notice Holder in accordance with Section 8(c), or (2) if the Holder fails to
deliver at or prior to the written confirmation of sale, the most recent
Prospectus, as amended or supplemented, and such Prospectus, as amended or
supplemented, corrected such untrue statement or omission or alleged untrue
statement or omission of a material fact and the delivery thereof was required
by law and would have constituted a complete defense to the claim in respect of
such untrue statement or omission or alleged untrue statement or omission.

     (b) Each Notice Holder agrees, severally and not jointly, to indemnify and
hold harmless the Initial Purchaser and each person, if any, who controls the
Initial Purchaser within the meaning of either Section 15 of the Securities Act
or Section 20 of the Exchange Act and the Company, and each person, if any, who
controls the Company within the meaning of either such Section, against any and
all loss, liability, claim, damage and expense described in the indemnity
contained in subsection (a) of this Section, as incurred, but only with respect
to untrue statements or omissions, or alleged untrue statements or omissions,
made in the Registration Statement (or any amendment thereto), or any
preliminary prospectus or the Prospectus (or any amendment or supplement
thereto) in reliance upon and in conformity with written information furnished
to the Company by such holder of Registrable Securities (which also
acknowledges the indemnity provisions herein) and each person, if any, who
controls any such holder of Registrable Securities expressly for use in the
Registration Statement (or any amendment thereto) or such preliminary
prospectus or the Prospectus (or any amendment or supplement thereto).

     The Initial Purchaser agrees to indemnify and hold harmless the Company,
the holders of Registrable Securities, and each person, if any, who controls
the Company or any holder of Registrable Securities within the meaning of
either Section 15 of the Securities Act or Section 20 of the Exchange Act
against any and all loss, liability, claim, damage and expense described in the
indemnity contained in subsection (a) of this Section, as incurred, but only
with respect to untrue statements or omissions, or alleged untrue statements or
omissions, made in the Registration Statement (or any amendment thereto), or
any preliminary prospectus or the Prospectus (or any amendment or supplement
thereto) in reliance upon and in conformity with written information furnished
to the Company by the Initial Purchaser expressly for use in the Registration
Statement (or any amendment thereto) or such preliminary prospectus or the
Prospectus (or any amendment or supplement thereto).

     (c) In case any action or proceeding (including any governmental
investigation) shall be instituted involving any person in respect of which
indemnity may be sought pursuant to the foregoing provisions, such person (the
"indemnified party") shall give notice as promptly as reasonably practicable to
the person against whom such indemnity may be sought (the "indemnifying party")
in writing, but failure to so notify an indemnifying party shall not relieve
such indemnifying party from any liability hereunder to the extent it is not
materially prejudiced as a result thereof and in any event shall not relieve it
from any liability which it may have otherwise than on account of this
indemnity agreement. An indemnifying party may participate at its own expense
in the defense of any such action; provided, however, that counsel


                                      14
<PAGE>


to the indemnifying party shall not (except with the consent of the indemnified
party) also be counsel to the indemnified party. In no event shall the
indemnifying parties be liable for fees and expenses of more than one counsel
(in addition to any local counsel) separate from their own counsel for all
indemnified parties in connection with any one action or separate but similar
or related actions in the same jurisdiction arising out of the same general
allegations or circumstances. No indemnifying party shall, without the prior
written consent of the indemnified parties, settle or compromise or consent to
the entry of any judgment with respect to any litigation, or any investigation
or proceeding by any governmental agency or body, commenced or threatened, or
any claim whatsoever in respect of which indemnification or contribution could
be sought under this Section 6 hereof (whether or not the indemnified parties
are actual or potential parties thereto), unless such settlement, compromise or
consent (i) includes an unconditional release of each indemnified party from
all liability arising out of such litigation, investigation, proceeding or
claim and (ii) does not include a statement as to or an admission of fault,
culpability or a failure to act by or on behalf of any indemnified party.

     (d) If at any time an indemnified party shall have requested an
indemnifying party to reimburse the indemnified party for fees and expenses of
counsel, such indemnifying party agrees that it shall be liable for any
settlement of the nature contemplated by Section 6(a)(ii) effected without its
written consent if (i) such settlement is entered into more than 45 days after
receipt by such indemnifying party of aforesaid request, (ii) such indemnifying
party shall have received notice of the terms of such settlement at least 30
days prior to such settlement being entered into and (iii) such indemnifying
party shall not have reimbursed such indemnified party in accordance with such
request prior to the date of such settlement.

     (e) If the indemnification provided for in this Section 6 is for any
reason unavailable to or insufficient to hold harmless an indemnified party in
respect of any losses, liabilities, claims, damages or expenses referred to
therein, then each indemnifying party shall contribute to the aggregate amount
of such losses, liabilities, claims, damages and expenses incurred by such
indemnified party, as incurred, in such proportion as is appropriate to reflect
the relative fault of the indemnifying party or parties on the one hand and of
the indemnified party on the other hand in connection with the statements or
omissions which resulted in such losses, liabilities, claims, damages or
expenses, as well as any other relevant equitable considerations.

     The relative fault of the Company on the one hand and the holders of the
Registrable Securities or the Initial Purchaser on the other hand shall be
determined by reference to, among other things, whether any such untrue or
alleged untrue statement of a material fact or omission or alleged omission to
state a material fact relates to information supplied by the Company or by the
holder of the Registrable Securities or the Initial Purchaser and the parties'
relative intent, knowledge, access to information and opportunity to correct or
prevent such statement or omission.

     The parties hereto agree that it would not be just and equitable if
contribution pursuant to this Section 6(e) were determined by pro rata
allocation or by any other method of allocation which does not take account of
the equitable considerations referred to above in this Section 6(e). The
aggregate amount of losses, liabilities, claims, damages, and expenses incurred
by an indemnified party and referred to above in this Section 6(e) shall be
deemed to include any legal or other expenses reasonably incurred by such
indemnified party in investigating, preparing

                                      15
<PAGE>

or defending against any litigation, or any investigation or proceeding by any
governmental agency or body, commenced or threatened, or any claim whatsoever
based upon any such untrue or alleged untrue statement or omission or alleged
omission.

     Notwithstanding the provisions of this Section 6, neither the holder of
any Registrable Securities nor the Initial Purchaser, shall be required to
indemnify or contribute any amount in excess of the amount by which the total
price at which the Registrable Securities sold by such holder of Registrable
Securities or unwritten by the Initial Purchaser, as the case may be, and
distributed to the public were offered to the public exceeds the amount of any
damages that such holder of Registrable Securities or the Initial Purchaser has
otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission.

     No person guilty of fraudulent misrepresentation (within the meaning of
Section 11(f) of the Securities Act) shall be entitled to contribution from any
person who was not guilty of such fraudulent misrepresentation.

     For purposes of this Section 6(e), each person, if any, who controls the
Initial Purchaser or any holder of Registrable Securities within the meaning of
Section 15 of the Securities Act or Section 20 of the Exchange Act shall have
the same rights to contribution as the Initial Purchaser or such holder, and
each person, if any, who controls the Company within the meaning of Section 15
of the Securities Act or Section 20 of the Exchange Act shall have the same
rights to contribution as the Company.

     Section 7. Information Requirements. The Company covenants that, if at any
time before the end of the Effectiveness Period the Company is not subject to
the reporting requirements of the Exchange Act, it will cooperate with any
Holder of Registrable Securities and take such further reasonable action as any
Holder of Registrable Securities may reasonably request in writing (including,
without limitation, making such reasonable representations as any such Holder
may reasonably request), all to the extent required from time to time to enable
such Holder to sell Registrable Securities without registration under the
Securities Act within the limitation of the exemptions provided by Rule 144 and
Rule 144A under the Securities Act and customarily taken in connection with
sales pursuant to such exemptions. Upon the written request of any Holder of
Registrable Securities, the Company shall deliver to such Holder a written
statement as to whether it has complied with such filing requirements, unless
such a statement has been included in the Company's most recent report required
to be filed and filed pursuant to Section 13 or Section 15(d) of Exchange Act.
Notwithstanding the foregoing, nothing in this Section 7 shall be deemed to
require the Company to register any of its securities (other than Common Stock)
under any section of the Exchange Act.


                                      16
<PAGE>


     Section 8. Miscellaneous. (a) No Conflicting Agreements. The Company is
not, as of the date hereof, a party to, nor shall it, on or after the date of
this Agreement, enter into, any agreement with respect to its securities that
conflicts with the rights granted to the Holders of Registrable Securities in
this Agreement. The Company represents and warrants that the rights granted to
the Holders of Registrable Securities hereunder do not in any way conflict with
the rights granted to the holders of the Company's securities under any other
agreements.

     (b) Amendments and Waivers. The provisions of this Agreement, including
the provisions of this sentence, may not be amended, modified or supplemented,
and waivers or consents to departures from the provisions hereof may not be
given, unless the Company has obtained the written consent of Holders of a
majority of the then outstanding Underlying Common Stock constituting
Registrable Securities (with Holders of LYONs deemed to be the Holders, for
purposes of this Section, of the number of outstanding shares of Underlying
Common Stock into which such LYONs are or would be convertible or exchangeable
as of the date on which such consent is requested). Notwithstanding the
foregoing, a waiver or consent to depart from the provisions hereof with
respect to a matter that relates exclusively to the rights of Holders of
Registrable Securities whose securities are being sold pursuant to a
Registration Statement and that does not directly or indirectly affect the
rights of other Holders of Registrable Securities may be given by Holders of at
least a majority of the Registrable Securities being sold by such Holders
pursuant to such Registration Statement; provided, that the provisions of this
sentence may not be amended, modified, or supplemented except in accordance
with the provisions of the immediately preceding sentence. Each Holder of
Registrable Securities outstanding at the time of any such amendment,
modification, supplement, waiver or consent or thereafter shall be bound by any
such amendment, modification, supplement, waiver or consent effected pursuant
to this Section 8(b), whether or not any notice, writing or marking indicating
such amendment, modification, supplement, waiver or consent appears on the
Registrable Securities or is delivered to such Holder.

     (c) Notices. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand delivery, by telecopier,
by courier guaranteeing overnight delivery or by first-class mail, return
receipt requested, and shall be deemed given (i) when made, if made by hand
delivery, (ii) upon confirmation, if made by telecopier, (iii) one (1) Business
Day after being deposited with such courier, if made by overnight courier or
(iv) on the date indicated on the notice of receipt, if made by first-class
mail, to the parties as follows:

          (w) if to a Holder of Registrable Securities that is not a Notice
     Holder, at the address for such Holder then appearing in the Registrar (as
     defined in the Indenture);

          (x) if to a Notice Holder, at the most current address given by such
     Holder to the Company in a Notice and Questionnaire or any amendment
     thereto;

          (y) if to the Company, to:

          Laboratory Corporation of America Holdings
          358 South Main Street
          Burlington, NC  27215
          Attention:  Bradford T. Smith, Executive Vice President,
                      General Counsel,


                                      17
<PAGE>


                      Corporate Compliance Officer and Secretary
          Telecopy No.:  (336) 226-3835

          and

          (z) if to the Initial Purchaser, to:

          Merrill Lynch & Co., Merrill Lynch, Pierce,
            Fenner & Smith Incorporated
          4 World Financial Center
          North Tower
          250 Vesey Street
          New York, New York  10080
          Attention:  Syndicate Department
          Telecopy No.:  (212) 449-1000

or to such other address as such person may have furnished to the other persons
identified in this Section 8(c) in writing in accordance herewith.

     (d) Approval of Holders. Whenever the consent or approval of Holders of a
specified percentage of Registrable Securities is required hereunder, the
Registrable Securities held by the Company or its affiliates (as such term is
defined in Rule 405 under the Securities Act) (other than the Initial Purchaser
or subsequent Holders of Registrable Securities if such subsequent Holders are
deemed to be such affiliates solely by reason of their holdings of such
Registrable Securities) shall not be counted in determining whether such
consent or approval was given by the Holders of such required percentage.

     (e) Successors and Assigns. Any person who purchases any Registrable
Securities from the Initial Purchaser shall be deemed, for purposes of this
Agreement, to be an assignee of the Initial Purchaser. This Agreement shall
inure to the benefit of and be binding upon the successors and assigns of each
of the parties and shall inure to the benefit of and be binding upon each
Holder of any Registrable Securities.

     (f) Counterparts. 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 original and all of which taken together
shall constitute one and the same agreement.

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

     (h) Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD
TO CONFLICTS OF LAWS PRINCIPLES THEREOF.

     (i) Severability. If any term, provision, covenant or restriction of this
Agreement is held to be invalid, illegal, void or unenforceable, the remainder
of the terms, provisions, covenants and restrictions set forth herein shall
remain in full force and effect and shall in no way be affected, impaired or
invalidated thereby, and the parties hereto shall use their


                                      18

<PAGE>


best efforts to find and employ an alternative means to achieve the same or
substantially the same result as that contemplated by such term, provision,
covenant or restriction, it being intended that all of the rights and
privileges of the parties shall be enforceable to the fullest extent permitted
by law.

     (j) Entire Agreement. This Agreement is intended by the parties as a final
expression of their agreement and is intended to be a complete and exclusive
statement of the agreement and understanding of the parties hereto in respect
of the subject matter contained herein and the registration rights granted by
the Company with respect to the Registrable Securities. Except as provided in
the Purchase Agreement, there are no restrictions, promises, warranties or
undertakings, other than those set forth or referred to herein, with respect to
the registration rights granted by the Company with respect to the Registrable
Securities. This Agreement supersedes all prior agreements and undertakings
among the parties with respect to such registration rights.

     (k) Termination. This Agreement and the obligations of the parties
hereunder shall terminate upon the expiration of the Effectiveness Period,
except for any liabilities or obligations under Sections 4, 5 or 6 hereof and
the obligations to make payments of and provide for liquidated damages under
Section 2(e) hereof to the extent such damages accrue prior to the end of the
Effectiveness Period, each of which shall remain in effect in accordance with
its terms.

               [Remainder of this page intentionally left blank]


                                      19

<PAGE>


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


                                        LABORATORY CORPORATION OF AMERICA
                                          HOLDINGS


                                        By: /s/ Bradford T. Smith
                                            -----------------------------
                                            Name:  Bradford T. Smith
                                            Title: Executive Vice President,
                                                   General Counsel, Corporate
                                                   Compliance Officer and
                                                   Secretary

Confirmed and accepted as
of the date first above written:


MERRILL LYNCH & CO.
     MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED


By: /s/ James Jackson
    ---------------------------------------------------
    Name:  James Jackson
    Title:    Director