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                                                                     EXHIBIT 4.3



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                         QUANTUM HEALTH RESOURCES, INC.


                                       AND


                        FIRST TRUST NATIONAL ASSOCIATION,
                                     Trustee


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                             Supplemental Indenture

                            Dated as of June 28, 1996

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



                                       To


                     Indenture, Dated as of October 8, 1993,
                   Between Quantum Health Resources, Inc. and
                  First Trust National Association, as Trustee,
               Relating to $86,250,000 Aggregate Principal Amount
        of 4 3/4% Convertible Subordinated Debentures Due October 1, 2000



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                             SUPPLEMENTAL INDENTURE


                  SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated
as of June 28, 1996, between Quantum Health Resources, Inc., a Delaware
corporation (the "Company"), having its principal office at Two Parkwood
Crossing, Suite 500, 310 East 96th Street, Suite 500, Indianapolis, Indiana,
46240, and First Trust National Association, a Minnesota corporation, as Trustee
(the "Trustee").

                             RECITALS OF THE COMPANY


                  WHEREAS the Company and the Trustee heretofore executed and
delivered an Indenture, dated as of October 8, 1993 (the "Indenture")
(capitalized terms used but not otherwise defined in this Supplemental Indenture
shall have the meanings ascribed to such terms in the Indenture); and

                  WHEREAS, pursuant to the Indenture, the Company issued and the
Trustee authenticated and delivered $86,250,000 aggregate principal amount of
the Company's 4 3/4% Convertible Subordinated Debentures Due October 1, 2000
(the "Debentures"); and

                  WHEREAS, pursuant to the Amended and Restated Agreement and
Plan of Merger (the "Merger Agreement"), dated as of May 1, 1996, by and among
Olsten Corporation, a Delaware corporation ("Olsten"), QHR Acquisition Corp., a
Delaware corporation that is a wholly owned subsidiary of Olsten ("Merger Sub"),
and the Company, on June 28, 1996, Merger Sub was merged with and into the
Company (the "Merger), with the Company as the surviving corporation, and each
issued and outstanding share of the Company's Common Stock, par value $.01 per
share ("Quantum Common Stock"), other than such Quantum Common Stock held by
stockholders exercising dissenter's rights under the General Corporation Law of
the State of Delaware, was converted into the right to receive fifty-eight one
hundredths (.58) of one share (the "Conversion Number") of Olsten's Class B
Common Stock, par value $.10 per share ("Class B Stock"); and

                  WHEREAS Section 13.11 of the Indenture provides that, in the
case of any merger of another Person into the Company which results in the
conversion of Quantum Common Stock, the Person resulting from such merger shall
execute and deliver to the Trustee a supplemental indenture providing that the
Holder of each Debenture then outstanding shall have the right thereafter,
during the period such Debenture shall be Convertible as specified in Section
13.1 of the Indenture, to convert such Debenture only into the kind and amount
of securities, cash or other assets receivable upon such merger by a holder of
the number of

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shares of Quantum Common Stock into which such Debenture might have been
converted immediately prior to such merger; and

                  WHEREAS, this Supplemental Indenture has been duly authorized
by all necessary corporate action on the part of the Company; and

                  WHEREAS the Company has delivered, or caused to be delivered,
to the Trustee, an Opinion of Counsel and Officers' Certificate, each stating
that this Supplemental Indenture complies with the requirements of the
Indenture.

                  NOW, THEREFORE, the Company hereby covenants and agrees with
the Trustee for the equal and proportionate benefit of all Holders of the
Debentures, as follows:

                  SECTION 1. Amendment of Certain Sections of' Indenture.
Subject to the other provisions hereof, the Indenture is hereby amended and
supplemented in the following respects:

                  (a) Section 13.4 of the Indenture is hereby amended and
         supplemented by adding the following at the end thereof:

                  "(j) From and after the effective time of the merger of QHR
         Acquisition Corp., a Delaware corporation ("Merger Sub"), with and into
         the Company pursuant to the Amended and Restated Agreement and Plan of
         Merger (the "Merger Agreement"), dated as of May 1, 1996, by and among
         Olsten Corporation, a Delaware corporation ("Olsten"), Merger Sub and
         the Company, which merger occurred on June 28, 1996, the Holder of each
         Debenture then outstanding shall have the right thereafter, during the
         period such Debenture shall be convertible as specified in Section
         13.1, to convert each such Debenture only into the number of shares of
         Olsten Class B Common Stock, par value $.10 per share, obtained by
         multiplying fifty-eight one hundredths (.58) by the number of shares of
         Common Stock of the Company into which such Debenture might have been
         converted immediately prior to such merger, assuming such holder of
         Common Stock of the Company is not a Constituent Person or an Affiliate
         of a Constituent Person, subject to such further adjustments as may be
         required by the provisions of this Indenture;" and

                  SECTION 2. Effect of Supplemental Indenture. Upon the
execution and delivery of this Supplemental Indenture by the Company and the
Trustee, the Indenture shall be supplemented in accordance herewith, and this
Supplemental Indenture shall form a part of

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the Indenture for all purposes, and every Holder of Securities heretofore or
hereafter authenticated and delivered under the Indenture shall be bound
thereby.

                  SECTION 3. Indenture Remains in Full Force and Effect. Except
as supplemented hereby, all provisions in the Indenture shall remain in full
force and effect.

                  SECTION 4. Indenture and Supplemental Indenture Construed
Together. This Supplemental Indenture is an indenture supplemental to the
Indenture, and forms a part of the Indenture for all purposes.

                  SECTION 5. Conflict with Trust Indenture Act. If any provision
of this Supplemental Indenture limits, qualifies or conflicts with any provision
of Sections 310 through 317, inclusive, of the Trust Indenture Act, which
provision imposes duties on any Person, the applicable provisions of Sections
310 through 317, inclusive, of the Trust Indenture Act shall control.

                  SECTION 6. Separability Clause. In case any provision in this
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

                  SECTION 7. Effect of Headings. The Article and Section
headings herein are for convenience only and shall not affect the construction
hereof.

                  SECTION 8. Benefits of Supplemental Indenture, Etc. Nothing in
this Supplemental Indenture, express or implied, shall give to any Person, other
than the parties hereto and thereto and their successors hereunder, any benefit
or any legal or equitable right, remedy or claim under this Supplemental
Indenture.

                  SECTION 9. Successors and Assigns. All covenants and
agreements in this Supplemental Indenture by the Company shall bind its
successors and assigns, whether so expressed or not.

                  SECTION 10. Trustee Not Responsible for Recitals. The recitals
contained herein shall be taken as the statements of the Company, and the
Trustee assumes no responsibility for their correctness. The Trustee makes no
representations as to the validity or sufficiency of this Supplemental
Indenture.

                  SECTION 11. Certain Duties and Responsibilities of the
Trustee. In entering into this Supplemental Indenture, the Trustee shall be
entitled to the benefit of every provision of the Indenture relating to the
conduct or affecting the liability of or affording protection to the Trustee,
whether or not elsewhere herein so provided.

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                  SECTION 12. Governing Law. This Supplemental Indenture shall
be governed by and construed in accordance with the laws of the State of New
York.

                  SECTION 13. Counterparts. This Supplemental Indenture may be
executed in counterparts, each of which, when so executed, shall be deemed to be
an original, but all such counterparts shall together constitute but one and the
same instrument.

                  IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed and attested, all as of the date and
year first above written.

                                       QUANTUM HEALTH RESOURCES, INC.


                                       By:
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                                       Title:
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Attest:


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Title:
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                                       FIRST TRUST NATIONAL ASSOCIATION,
                                       as Trustee


                                       By:
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                                       Title:
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Attest:


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Title:
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