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                                                                     EXHIBIT 4.3

                                DEED OF GUARANTEE

THIS DEED OF GUARANTEE is made on 27th March, 2003 by CIBA SPECIALTY CHEMICALS
HOLDING INC., (the GUARANTOR) in favour of the Relevant Account Holders (as
defined in the Deed of Covenant referred to below) and the holders for the time
being of the Notes (as defined below) and the interest coupons (if any)
appertaining to the Notes (COUPONS), the Coupons being attached on issue to
Definitive Note(s) (as defined below). Each Relevant Account Holder, each holder
of a Note and each holder of a Coupon is a HOLDER.

WHEREAS:

(A)   CIBA SPECIALTY CHEMICALS CORPORATION, CIBA SPECIALTY CHEMICALS PLC, CIBA
      SPEZIALITATENCHEMIE HOLDING DEUTSCHLAND GMBH, CIBA SPECIALTY CHEMICALS
      EUROFINANCE LTD. (the ISSUERS and each an ISSUER) and the Guarantor have
      entered into an amended and restated Program Agreement (the PROGRAM
      AGREEMENT, which expression includes the same as it may be amended or
      supplemented from time to time) dated 27th March, 2003 with the Dealers
      named therein, which amends and restates the amended and restated program
      agreement entered into by, inter alia, Ciba Specialty Chemicals
      Corporation, Ciba Specialty Chemicals PLC and Ciba Spezialitatenchemie
      Holding Deutschland GmbH dated 27th March, 2002 (the PRINCIPAL PROGRAM
      AGREEMENT), under which each Issuer proposes from time to time to issue
      Euro Medium Term Notes (the NOTES, such expression to include each
      Definitive Note issued by an Issuer and each Global Note issued by an
      Issuer (where DEFINITIVE NOTE and GLOBAL NOTE have the meanings ascribed
      thereto in the Agency Agreement defined below) and to include any receipts
      issued in respect of Notes repayable in instalments);

(B)   each Issuer has executed a Deed of Covenant of even date (the DEED OF
      COVENANT) relating to Global Notes issued by that Issuer pursuant to the
      Program Agreement;

(C)   the Issuers and the Guarantor have entered into an amended and restated
      agency agreement (the AGENCY AGREEMENT, which expression includes the same
      as it may be amended or supplemented from time to time) dated 27th March,
      2003 with the Paying Agents named therein; and

(D)   this Deed of Guarantee amends and restates the amended and restated Deed
      of Guarantee made by the Guarantor dated 27th March, 2002, and does not
      affect any Notes issued pursuant to the Principal Program Agreement prior
      to the date hereof.

NOW THIS DEED WITNESSES as follows:

1.    Guarantee: The Guarantor irrevocably and unconditionally undertakes to
      secure by way of deed poll to each Holder the due and punctual payment as
      stipulated in an Issuer's Note or Coupon or under its Deed of Covenant, as
      the case may be. The Guarantor therefore undertakes to pay on first demand
      of such a Holder, irrespective of the validity and the legal effects of
      the above mentioned relationship in respect of a Note or Coupon or Deed of
      Covenant and waiving all rights of objection and defence arising therefrom
      any amount not paid by the relevant Issuer (including any premium or any
      other amounts of whatever nature or additional amounts) upon receipt of
      the written request for payment by such Holder and the confirmation in
      writing by the Agent that the relevant Issuer has not made such payments
      on the dates specified and in the amount called under the Guarantee. The
      Guarantor hereby expressly undertakes and secures that payments under this
      Guarantee will not be less than as
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      stipulated in an Issuer's Note or Coupon. In implementation of this
      undertaking and in case Swiss withholding taxes are imposed in respect of
      payments made under this Guarantee, the Guarantor undertakes, as a
      separate and independent obligation, to pay an increased amount on the
      relevant Note or Coupon so that the payment received by the Noteholder or
      Couponholder shall equal the amount actually stipulated in such Note or
      Coupon (assuming no such withholding applies).

2.    Guarantor's Obligations Continuing: The Guarantor's obligations under this
      Guarantee are and will remain in full force and effect by way of
      continuing security until no sum remains payable under any Note, any
      Coupon or the Deed of Covenant. Furthermore, these obligations of the
      Guarantor are additional to, and not instead of, any security or other
      guarantee or indemnity at any time existing in favour of a Holder, whether
      from the Guarantor or otherwise. The Guarantor irrevocably waives all
      notices and demands whatsoever, except as provided herein.

3.    Repayment to the Issuer: If any payment received by a Holder is, on the
      subsequent liquidation or insolvency of the relevant Issuer, avoided under
      any laws relating to liquidation or insolvency, such payment will not be
      considered as having discharged or diminished the liability of the
      Guarantor and this Guarantee will continue to apply as if such payment had
      at all times remained owing by the relevant Issuer.

4.    Status of Guarantee: The payment obligations of the Guarantor under this
      Guarantee constitute direct, unconditional and (subject to clause 5 below)
      unsecured obligations of the Guarantor and (subject as aforesaid) rank and
      will rank pari passu with all other outstanding unsecured and
      unsubordinated indebtedness and monetary obligations of the Guarantor,
      present or future, including those in respect of deposits (other than
      obligations preferred by law).

5.    Negative Pledge of the Guarantor: So long as any of the Notes remains
      outstanding, but not later than the time when payment for the full amount
      of principal and interest in respect of all outstanding Notes has been
      duly provided for, the Guarantor will procure that no Indebtedness of the
      Guarantor which is represented by bonds, notes or other securities which
      in any such case are listed or capable of being listed on any recognised
      Stock Exchange will be secured upon any of the present or future assets or
      revenues of the Guarantor unless all amounts payable under this Guarantee
      are secured equally and rateably with such other security or such other
      security or guarantee is granted to the Notes and Coupons as shall have
      been approved by an Extraordinary Resolution of the Noteholders. Any
      reference to an obligation being guaranteed shall include a reference to
      an indemnity being given in respect of payment thereof.

      As used herein INDEBTEDNESS means all indebtedness for money borrowed that
      is created, assumed, incurred or guaranteed in any manner by the Guarantor
      or for which the Guarantor is otherwise responsible or liable.

6.    Tax Gross-up: All payments in respect of the Notes by the Guarantor shall
      be made without withholding or deduction for, or on account of, any
      present or future taxes, duties, assessments or governmental charges of
      whatever nature (TAXES) imposed or levied by or on behalf of Switzerland,
      or any political sub-division of, or any authority in, or of, Switzerland
      having power to tax, unless the withholding or deduction of the Taxes is
      required by law. In that event, the Guarantor will pay such additional
      amounts as may be necessary in order that the net amounts received by the
      Noteholders and Couponholders after the withholding or deduction shall
      equal the respective amounts which would have been receivable in respect
      of the Notes or, as the case may be, Coupons in the absence of the
      withholding or deduction;


                                                                               2
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      except that no additional amount shall be payable in relation to any
      payment in respect of any Note or Coupon:

      (i)   by or on behalf of a person liable to such tax, duty or charge in
            respect of such Note, Receipt or Coupon by reason of his having some
            connection with Switzerland other than the mere holding or ownership
            of such Note, Receipt or Coupon; and/or

      (ii)  presented for payment to the relevant Issuer more than 30 days after
            the Relevant Date (as defined in Condition 7(f) of the Terms and
            Conditions of the relevant Notes) except to the extent that a holder
            would have been entitled to additional amounts on presenting the
            same for payment on the last day of the period of 30 days; and/or

      (iii) to, or to a third party on behalf of, a holder who would be able to
            avoid such withholding or deduction by making a declaration of
            non-residence or similar claim for exemption but fails to do so;
            and/or

      (iv)  where such withholding or deduction is imposed on a payment to an
            individual and is required to be made pursuant to any European Union
            Directive on the taxation of savings implementing the conclusions of
            the ECOFIN Council meeting of 26th-27th November, 2000, or any law
            implementing or complying with, or introduced in order to conform
            to, such Directive; and/or

      (v)   presented for payment by or on behalf of a holder who would have
            been able to avoid such withholding or deduction by presenting the
            relevant Note or Coupon to another Paying Agent in a Member State of
            the EU.

7.    Power to execute: The Guarantor hereby warrants, represents and covenants
      with each Holder that it has all corporate power, and has taken all
      necessary corporate or other steps, to enable it to execute, deliver and
      perform this Guarantee, and that this Guarantee constitutes a legal, valid
      and binding obligation of the Guarantor, enforceable in accordance with
      its terms subject to applicable bankruptcy, reorganisation, insolvency,
      fraudulent transfer, moratorium and other similar laws affecting
      creditor's rights generally from time to time in effect, and to general
      principles of equity, regardless of whether considered in a proceeding in
      law or at equity.

8.    Deposit of Guarantee: This Guarantee shall take effect as a Deed Poll for
      the benefit of the Holders from time to time and for the time being. This
      Guarantee shall be deposited with and held by The Chase Manhattan Bank for
      the benefit of the Holders until all the obligations of the Guarantor
      hereunder have been discharged in full.

9.    Production of Guarantee: The Guarantor hereby acknowledges the right of
      every Holder to the production of, and the right of every Holder to obtain
      (upon payment of a reasonable charge) a copy of, this Guarantee, and
      further acknowledges and covenants that the obligations binding upon it
      contained herein are owed to, and shall be for the account of, each and
      every Holder, and that each Holder shall be entitled severally to enforce
      the said obligations against the Guarantor.

10.   Subrogation: Until all amounts which may be payable under the Notes, the
      Coupons and/or the Deed of Covenant have been irrevocably paid in full,
      the Guarantor shall not exercise any rights of subrogation in respect of
      any rights of any Holder or claim in competition with the Holders against
      the relevant Issuer.


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11.   Governing Law and Jurisdiction: This Guarantee is governed by and shall be
      construed in accordance with English law. The Guarantor irrevocably agrees
      for the benefit of each Holder that the courts of England are to have
      jurisdiction to settle any disputes which may arise out of or in
      connection with this Guarantee and that accordingly any suit, action or
      proceedings arising out of or in connection with this Guarantee (together
      referred to as PROCEEDINGS) may be brought in the courts of England.

      The Guarantor irrevocably waives any objection which it may have now or
      hereafter to the laying of the venue of the Proceedings in the courts of
      England and irrevocably agrees that a final judgment in any Proceedings
      brought in the courts of England shall be conclusive and binding upon the
      Guarantor and may be enforced in the courts of any other jurisdiction.
      Nothing contained in this clause shall limit any right to take Proceedings
      against the Guarantor in any other court of competent jurisdiction, nor
      shall the taking of Proceedings in none or more jurisdictions preclude the
      taking of Proceedings in any other jurisdiction, whether concurrently or
      not.

      No rights are conferred on any person under the Contracts (Rights of Third
      Parties) Act 1999 to enforce any term of this Global Note, but this does
      not affect any right or remedy of any person which exists or is available
      apart from that Act.

      The Guarantor hereby appoints Ciba Specialty Chemicals PLC as its agent
      for service of process in England in respect of any Proceedings and
      undertakes that in the event of it ceasing so to act it will appoint
      another person as its agent for that purpose.

IN WITNESS whereof this Guarantee has been manually executed as a deed poll on
behalf of the Guarantor.

Executed as a deed                   )
by CIBA SPECIALTY CHEMICALS          )           KIRK ERSTLING
HOLDING INC.                         )
acting by                            )           OLIVER STRUB
and                                  )
                                     )
acting under the authority of        )
that Company in the presence of:     )


Witness's   A. STEINER
Signature:  .......................................

            A.STEINER
Name:       .......................................

            C/o CIBA SPECIALTY CHEMICALS INC.
Address:    .......................................
            CH-4002 BASEL
            .......................................


Dated 27th March,  2003


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                                                                  CONFORMED COPY

                                27TH MARCH, 2003



                      CIBA SPECIALTY CHEMICALS HOLDING INC.
                                  AS GUARANTOR




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                                DEED OF GUARANTEE

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                                     LONDON