EXHIBIT 4

                      FOURTH AMENDMENT TO CREDIT AGREEMENT


     This Fourth Amendment to Credit  Agreement (the  "Amendment") is made as of
this 27th day of April,  2001 by and among AMERICAN MEDICAL SECURITY GROUP, INC.
(the "Borrower"),  the Lenders named in the Credit Agreement (the "Lenders") and
LASALLE BANK NATIONAL ASSOCIATION, as Agent and Swing Line Lender (the "Agent").

                                   WITNESSETH

     WHEREAS,  the  Borrower,  the Agent and the  Lenders  are  parties  to that
certain  Credit  Agreement,  dated as of March 24, 2000, as amended  pursuant to
that certain First Amendment to Credit Agreement,  dated as of July 18, 2000, as
further amended pursuant to that certain Second  Amendment to Credit  Agreement,
dated as of November 10, 2000, and as further  amended  pursuant to that certain
Third Amendment to Credit Agreement, dated as of January 29, 2001 (collectively,
the "Credit Agreement); and

     WHEREAS, the parties desire to further amend the Credit Agreement,  as more
fully set forth herein.

     NOW, THEREFORE,  in consideration of the mutual agreements herein contained
and other  good and  valuable  consideration,  the  adequacy  of which is hereby
acknowledged, and subject to the terms and conditions hereof, the parties hereto
agree as follows:

SECTION 1. DEFINITIONS.  Unless otherwise defined herein,  all capitalized terms
shall have the meaning given to them in the Credit Agreement.

SECTION 2. WAIVER OF CERTAIN  COVENANT  DEFAULTS.  As of March 31, 2001, AMS has
failed to comply with  Section  6.19.1 of the Credit  Agreement.  Such  failure,
unless  waived,  would  constitute  an Event of Default under Section 7.3 of the
Credit Agreement.  Subject to the terms hereof, the Agent and the Lenders hereby
waive  compliance with Section 6.19.1 of the Credit  Agreement,  as of March 31,
2001, and agree,  as of such date, that AMS may permit its Fixed Charge Coverage
Ratio to be less than 2.50:1.

     As of March 31, 2001,  AMS has failed to comply with Section  6.19.2 of the
Credit  Agreement.  Such failure,  unless waived,  would  constitute an Event of
Default under Section 7.3 of the Credit Agreement.  Subject to the terms hereof,
the Agent and the Lenders  hereby waive  compliance  with Section  6.19.2 of the
Credit Agreement, as of March 31, 2001, and agree, as of such date, that AMS may
permit its Interest Coverage Ratio to be less than 5.50:1.

     Except as expressly set forth herein, the above-referenced  waivers are not
intended to be and shall not be construed as a waiver or amendment of any of the
terms and provisions of the Credit Agreement,  which terms and provisions remain
in full force and effect.  Furthermore,  such  waivers  shall not  constitute  a
future waiver of compliance  with any  financial  covenants or other  provisions
under the Credit Agreement.


SECTION 3. AMENDMENTS TO CREDIT AGREEMENT.

     3.1 The  definition  of  "Applicable  Margin"  in  Article I of the  Credit
Agreement  is hereby  deleted  in its  entirety  and  amended by  inserting  the
following in its stead:

<PAGE>
          "Applicable  Margin" means, with respect to Eurodollar Advances at any
     time,  2.50%  per  annum  (unless a Default  or an  Unmatured  Default  has
     occurred that is continuing).

          Notwithstanding  anything to the contrary  contained  herein, if as of
     September 30, 2001 First Union  National  Bank,  National  Association is a
     Lender  under the Credit  Agreement,  then all Loans  which are  Eurodollar
     Loans shall  accrue  interest  at the  Eurodollar  Rate with an  Applicable
     Margin of 3.00% per annum  (unless a Default or an  Unmatured  Default  has
     occurred  that is  continuing)  effective  as of the next  Interest  Period
     following  September 30, 2001 if the then existing Interest Period does not
     end on September 30, 2001; PROVIDEDHOWEVER,  that in the event that (A) the
     Applicable  Margin is increased to 3.00% per annum as of September 30, 2001
     and (B) Borrower makes an additional  commitment reduction of $5,000,000 on
     or before July 15, 2002 (the "Additional Commitment Reduction") in addition
     to the scheduled mandatory  commitment  reductions set forth in Section 2.8
     of the Credit  Agreement,  then all Loans which are Eurodollar  Loans shall
     accrue interest at the Eurodollar  Rate with an Applicable  Margin of 2.50%
     per annum  (unless a Default or an Unmatured  Default has occurred  that is
     continuing)  effective as of the next Interest Period following  receipt of
     such Additional  Commitment Reduction;  providedfurther,  that in the event
     that Borrower fails to make the Additional Commitment  Reduction,  then all
     Loans which are  Eurodollar  Loans shall accrue  interest at the Eurodollar
     Rate with an  Applicable  Margin of 3.25% per annum (unless a Default or an
     Unmatured Default has occurred that is continuing) effective as of the next
     Interest  Period  following  July 15,  2002 if the then  existing  Interest
     Period does not end on July 15, 2002."

     3.2  Section  2.8(a)  of the  Credit  Agreement  is hereby  deleted  in its
entirety and amended by inserting the following in its stead:

          "2.8.MANDATORY  COMMITMENT  REDUCTIONS.  (a) The Aggregate  Commitment
     shall be automatically and permanently  reduced to the following amounts on
     the following dates:

<TABLE>
<CAPTION>
                           DATE             AVAILABILITY REDUCTION              AGGREGATE COMMITMENT
<S>               <C>                       <C>                                 <C>
                  November 10, 2000         $ 5,000,000                         $40,000,000
                  April 27, 2001            $ 4,842,228                         $35,157,772
                  February 15, 2002         $ 5,000,000                         $30,157,772
                  February 15, 2003         $10,000,000                         $20,157,772
                  February 15, 2004         $10,000,000                         $10,157,772
                  February 15, 2005         $10,157,772                         $         0
</TABLE>

          PROVIDED,   HOWEVER,  that  in  the  event  that  Borrower  makes  the
     Additional  Commitment  Reduction of $5,000,000 on or before July 15, 2002,
     then the  Aggregate  Commitment  shall  be  automatically  and  permanently
     reduced as follows:

<TABLE>
<CAPTION>
                  DATE                      AVAILABILITY REDUCTION              AGGREGATE COMMITMENT
<S>               <C>                       <C>                                 <C>
                  April 27, 2001            $ 4,842,228                         $35,157,772
                  February 15, 2002         $ 5,000,000                         $30,157,772
                  Date of Additional
                  Commitment Reduction      $ 5,000,000                         $25,157,772
                  February 15, 2003         $10,000,000                         $15,157,772
                  February 15, 2004         $10,000,000                         $ 5,157,772
                  February 15, 2005         $5,157,772                          $   0"
</TABLE>
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<PAGE>

     3.2  Section  6.19.1  of the  Credit  Agreement  is hereby  deleted  in its
entirety and amended by inserting the following in its stead:

          "6.19.1  FIXED CHARGE  COVERAGE  RATIO.  AMS will not permit its Fixed
     Charge Coverage Ratio,  determined as of the end of each Fiscal Quarter for
     the period of four Fiscal Quarters ending on such date, to be less than (a)
     1.50 to 1.0 from  January 1, 2001 through  March 31, 2001,  (b) 1.30 to 1.0
     from April 1, 2001 through June 30, 2001, (c) 1.30 to 1.0 from July 1, 2001
     through  September  30, 2001,  (d) 1.75 to 1.0 from October 1, 2001 through
     December  31, 2001,  (e) 3.00 to 1.0 from January 1, 2002 through  December
     31, 2002,  and (f) 3.25 to 1.0 from  January 1 through  December 31 of each
     year  thereafter;  PROVIDED,  HOWEVER,  there  shall be  excluded  from the
     calculation  of EBITDA within the Fixed Charge  Coverage Ratio the one-time
     charges relating to the pre-tax reserve  strengthening in the third quarter
     of 2000 and the Minnesota  special  assessment in the third quarter of 2000
     for AMS and its  Subsidiaries  and also the balloon payment due in the year
     2004 on the loan made by M&I  Marshall & Ilsley Bank that is secured by the
     real  property of AMS and it  Subsidiaries  located at 3100 AMS  Boulevard,
     Green Bay, Wisconsin 54313."

     2.3  Section  6.19.2  of the  Credit  Agreement  is hereby  deleted  in its
entirety and amended by inserting the following in its stead:

          "6.19.2  INTEREST  COVERAGE  RATIO.  AMS will not permit its  Interest
     Coverage  Ratio,  determined  as of the end of each Fiscal  Quarter for the
     period of four  Fiscal  Quarters  ending on such date,  to be less than (a)
     3.50 to 1.0 from  January 1, 2001 through  March 31, 2001,  (b) 3.25 to 1.0
     from April 1, 2001 through June 30, 2001, (c) 3.00 to 1.0 from July 1, 2001
     through  September  30, 2001,  (d) 4.00 to 1.0 from October 1, 2001 through
     December 31, 2001 and (e) 6.00 to 1.0 from January 1 through  December 1 of
     each year thereafter;  PROVIDED,  HOWEVER, there shall be excluded from the
     calculation  of EBITDA  within the  Interest  Coverage  Ratio the  one-time
     charges relating to the pre-tax reserve  strengthening in the third quarter
     of 2000 and the Minnesota  special  assessment in the third quarter of 2000
     for AMS and its Subsidiaries."

     2.4  Section  6.19.5  of the  Credit  Agreement  is hereby  deleted  in its
entirety and amended by inserting the following in its stead:

          "6.19.5  STATUTORY  CAPITAL AND  SURPLUS.  AMS will at all times cause
     UWLIC to maintain a Statutory  Capital and Surplus of not less than the sum
     of $130,000,000,  plus (b) 50% of the positive  Statutory Net Income earned
     by UWLIC in each Fiscal Quarter ending after March 31, 2001 and on or prior
     to the date of determination (excluding changes in unrealized gain/loss)."

SECTION  3.  CONDITIONS  PRECEDENT.  The  effectiveness  of  this  Amendment  is
expressly conditioned upon satisfaction of the following conditions precedent:


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<PAGE>


     3.1 The Agent and the Lenders shall have received  copies of this Amendment
duly executed by the Borrower.

     3.2 The Agent  shall have  received,  for the  benefit of the Agent and the
Lenders, an amendment fee of $175,789 due and payable and deemed fully earned on
the date hereof.

     3.3 The Agent and the Lenders  shall have  received  such other  documents,
certificates and assurances as they shall reasonably request.

SECTION 4.  REAFFIRMATION  OF THE BORROWER.  The Borrower hereby  represents and
warrants  to the  Agent and the  Lenders  that (i) the  warranties  set forth in
Article 5 of the  Credit  Agreement  are true and  correct on and as of the date
hereof,  except to the extent (a) that any such warranties  relate to a specific
date, or (b) changes  thereto are a result of  transactions  for which the Agent
and the Lenders have  granted  their  consent;  (ii) the Borrower is on the date
hereof  in  compliance  with all of the terms  and  provisions  set forth in the
Credit Agreement as hereby amended;  and (iii) upon execution hereof no Event of
Default has occurred and is continuing or has not previously been waived.

SECTION 5. FULL FORCE AND EFFECT. Except as herein amended, the Credit Agreement
and all other Loan Documents shall remain in full force and effect.

SECTION  6.  COUNTERPARTS.  This  Amendment  may be  executed  in  two  or  more
counterparts,  each of  which  shall be  deemed  an  original,  but all of which
together shall constitute one and the same document.

                            [SIGNATURE PAGE FOLLOWS]


                                     - 4 -
<PAGE>



     IN WITNESS WHEREOF,  the parties hereto have executed this Amendment on the
day and year specified above.

                                 AMERICAN MEDICAL SECURITY GROUP, INC.


                                 By: /S/ CAROL P. SANDERS
                                 Name:    Carol P. Sanders
                                 Title: Vice President and Treasurer


                                 LASALLE BANK NATIONAL ASSOCIATION

                                 By: /S/ LINDA A. WHITTAKER
                                 Name:    Linda A. Whittaker
                                 Title:   Assistant Vice President


                                 FIRST UNION NATIONAL BANK, NATIONAL ASSOCIATION

                                 By: /S/ THOMAS L. STITCHBERRY
                                 Name:    Thomas L. Stitchberry
                                 Title:   Senior Vice President


                                 ASSOCIATED BANK GREEN BAY, NATIONAL ASSOCIATION

                                 By: /S/ DENIS F. HOGAN
                                 Name:    Denis F. Hogan
                                 Title:   Senior Vice President



                                     - 5 -
<PAGE>



     ACKNOWLEDGMENT AND AGREEMENT OF GUARANTOR

     The undersigned,  AMERICAN MEDICAL SECURITY HOLDINGS, INC., hereby ratifies
and reaffirms that certain  Guaranty dated March 24, 2000 (the  "Guaranty") made
by the  undersigned  in favor of the Agent and the Lenders and each of the terms
and provisions contained therein, and agrees that the Guaranty continues in full
force  and  effect  following  the  execution  and  delivery  of  the  foregoing
Amendment.  The undersigned represents and warrants to the Agent and the Lenders
that the Guaranty was, on the date of the execution  and delivery  thereof,  and
continues to be, the valid and binding obligation of the undersigned enforceable
in accordance  with its terms and that the undersigned has no claims or defenses
to the enforcement of the rights and remedies of the Agent and the Lenders under
the Guaranty.

     IN WITNESS WHEREOF, this Acknowledgment and Agreement of Guarantor has been
duly authorized as of this 27th day of April, 2001.

                                 AMERICAN MEDICAL SECURITY HOLDINGS, INC.


                                 By:      /S/ CAROL P. SANDERS
                                 Name:    Carol P. Sanders
                                 Title:   Vice President and Treasurer


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