Exhibit 4.3


                      SECOND AMENDMENT TO CREDIT AGREEMENT


         THIS SECOND AMENDMENT TO CREDIT AGREEMENT (the  "Amendment"),  dated as
of March 13, 1998, is entered into by and between SPSS INC. (the "Borrower") and
BANK OF AMERICA NATIONAL TRUST AND SAVINGS  ASSOCIATION  (successor by merger to
Bank of America Illinois) (the "Bank").


                                    RECITALS

         A. The Borrower and the Bank are parties to a Credit Agreement dated as
of March 15, 1996,  as amended (the  "Credit  Agreement")  pursuant to which the
Bank has extended  certain credit  facilities to the Borrower and certain of its
Subsidiaries, on and subject to the terms and conditions set forth therein.

         B. The  Borrower has  requested  that the Bank agree to an extension of
the "Availability Period", as defined in the Credit Agreement.

         C. The Bank is willing to extend the Availability Period subject to the
terms and conditions of this Amendment.

         NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which are hereby acknowledged, the parties hereto hereby agree as follows:

         1. Defined Terms.  Unless otherwise  defined herein,  capitalized terms
used  herein  shall have the  meanings,  if any,  assigned to them in the Credit
Agreement.

         2.  Amendment to Credit Agreement.

                  (a) Section 1.01 of the Credit  Agreement  shall be amended at
the defined term  "Availability  Period" by amending and restating  such defined
term in its entirety as follows:

                    "'Availability Period': the period commencing on the date of
                    this Agreement and ending on the date that is the earlier to
                    occur of (a) April 30,  1998,  and (b) the date on which the
                    Bank's commitment to extend credit hereunder terminates."

         3.  Representations and Warranties.  The Borrower hereby represents and
warrants to the Bank as follows:

                  (a) No  Default  or  Event  of  Default  has  occurred  and is
continuing.

                  (b) The execution, delivery and performance by the Borrower of
this  Amendment have been duly  authorized by all necessary  corporate and other
action  and do not and  will not  require  any  registration  with,  consent  or
approval  of,  notice to or action by, any person  (including

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any governmental authority) in order to be effective and enforceable. The Credit
Agreement as amended by this Amendment  constitutes the legal, valid and binding
obligations  of the  Borrower,  enforceable  against it in  accordance  with its
respective terms, without defense, counterclaim or offset.

                  (c)  All   representations  and  warranties  of  the  Borrower
contained in the Credit Agreement are true and correct.

                  (d) The Borrower is entering into this  Amendment on the basis
of its own investigation and for its own reasons, without reliance upon the Bank
or any other person.

         4. Reservation of Rights. The Borrower acknowledges and agrees that the
execution  and  delivery  by the Bank of this  Amendment  shall not be deemed to
create a course of dealing or  otherwise  obligate  the Bank to execute  similar
amendments under the same or similar circumstances in the future.

         5.  Miscellaneous.

                  (a) Except as herein expressly amended,  all terms,  covenants
and  provisions  of the Credit  Agreement are and shall remain in full force and
effect and all  references  therein and in the other  Credit  Documents  to such
Credit  Agreement shall  henceforth  refer to the Credit Agreement as amended by
this Amendment. This Amendment shall be deemed incorporated into, and a part of,
the Credit Agreement.

                  (b) This  Amendment  shall be  binding  upon and  inure to the
benefit of the parties  hereto and thereto and their  respective  successors and
assigns.  No third party  beneficiaries  are  intended in  connection  with this
Amendment.

                  (c) This  Amendment  shall be  governed  by and  construed  in
accordance with the law of the State of Illinois.

                  (d)  This   Amendment   may  be  executed  in  any  number  of
counterparts,  each  of  which  shall  be  deemed  an  original,  but  all  such
counterparts together shall constitute but one and the same instrument.  Each of
the parties  hereto  understands  and agrees that this  document  (and any other
document  required  herein) may be delivered by any party thereto  either in the
form  of an  executed  original  or  an  executed  original  sent  by  facsimile
transmission  to be followed  promptly by mailing of a hard copy  original,  and
that receipt by the Bank of a facsimile transmitted document purportedly bearing
the  signature of the Borrower  shall bind the Borrower  with the same force and
effect as the  delivery  of a hard copy  original.  Any  failure  by the Bank to
receive the hard copy executed  original of such document shall not diminish the
binding effect of receipt of the facsimile transmitted executed original of such
document which hard copy page was not received by the Bank.

                  (e)  This  Amendment,  together  with  the  Credit  Agreement,
contains the entire and exclusive agreement of the parties hereto with reference
to the matters discussed herein and therein. This Amendment supersedes all prior
drafts and  communications  with  respect  thereto.


<PAGE>

This  Amendment may not be amended  except in accordance  with the provisions of
Section 9.05 of the Credit Agreement.

                  (f) If any term or provision of this Amendment shall be deemed
prohibited  by or invalid under any  applicable  law,  such  provision  shall be
invalidated without affecting the remaining  provisions of this Amendment or the
Credit Agreement, respectively.

                  (g) Borrower  covenants to pay to or reimburse the Bank,  upon
demand,  for all costs  and  expenses  (including  allocated  costs of  in-house
counsel) incurred in connection with the development,  preparation, negotiation,
execution and delivery of this Amendment.

                  IN WITNESS  WHEREOF,  the  parties  hereto have  executed  and
delivered this Amendment as of the date first above written.


                                  SPSS INC.


                                  By:        /s/ Robert Brinkmann

                                  Title:     Controller




                                  BANK OF AMERICA NATIONAL TRUST
                                  AND SAVINGS ASSOCIATION


                                  By:        /s/ Douglas C. Watson

                                  Title:     Vice President