EXHIBIT 10.6

                               SECOND AMENDMENT TO
                                CREDIT AGREEMENT

     THIS  SECOND  AMENDMENT  TO  CREDIT  AGREEMENT  is  made  and  dated  as of
January 15,  1999 (the "Second  Amendment")  among SIERRA HEALTH SERVICES,  INC.
(the "Company"),  the Banks now party to the Credit Agreement referred to below,
DEUTSCHE BANK AG, New York and/or  Cayman  Island  Branches (the "New Bank") and
BANK OF AMERICA  NATIONAL  TRUST AND  SAVINGS  ASSOCIATION,  a national  banking
association,  as  Administrative  Agent (the  "Agent"),  and amends that certain
Credit  Agreement dated as of October 30, 1998, as amended by that certain First
Amendment  dated as of  November 23,  1998 (as further  amended or modified from
time to time, the "Credit Agreement").

                                                     RECITALS

     WHEREAS, the Company has requested the Agent and the Banks to amend certain
provisions of the Credit  Agreement,  and the Agent and the Banks are willing to
do so, on the terms and conditions specified herein;

     WHEREAS, the New Bank wishes to be added to the Credit Agreement as a Bank,
and the Company,  the Agent and the existing Banks are willing to permit the New
Bank to be so added;

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

     1.  Terms.  All terms used  herein  shall have the same  meanings as in the
Credit Agreement unless otherwise defined herein.

         2.       Amendment.  The Credit Agreement is hereby amended as follows:

                  2.1      Amendment to Section 8.10.

     (a) Section 8.10 of the Credit  Agreement  is hereby  amended by adding the
following clause immediately after the phrase  "notwithstanding  the foregoing,"
in the seventh line from the end of such Section:

     "(i) any  Wholly-Owned  Subsidiaries  may declare and pay  dividends to the
Company and (ii) "

                  2.2      Amendment to Section 8.14.

     (a) Clause (ii) of subsection  (b) of Section 8.14 of the Credit  Agreement
is hereby  amended by  replacing  the phrase "for the period  commencing  on the
Closing Date and

                                                         1

     ending on the date of determination"  and with the following  phrase:  "for
each Fiscal  Quarter  ending after the Closing Date and on or before the date of
determination,".

                  2.3      Amendment to Section 8.17.

     (a) The  proviso at the end of  Section  8.17 of the  Credit  Agreement  is
hereby  amended by inserting the  following  clause  immediately  after the word
"foregoing":  "the Company may consummate any of the  transactions  set forth on
Schedule 8.17 and".

                  2.4      Amendment to Section 9.02.

     (a) The following  sentence shall be added to the end of the first sentence
of Section 9.02:  "Upon any  acceleration of the Loans pursuant to the foregoing
provisions,  the Company  shall  deposit  with the Agent cash  collateral  in an
amount  equal to the  aggregate  undrawn  amount of all  Letters of Credit  then
outstanding (the "Maximum Available Amount");  provided that in the event of any
drawing  under any Letter of Credit  thereafter,  the Agent  shall use such cash
collateral to reimburse such drawing and provided  further that, in the event of
any  cancellation  or expiration of any Letter of Credit,  the Agent shall apply
the difference  between the Maximum  Available Amount  immediately prior to such
cancellation or expiration and the Maximum  Available Amount  immediately  after
such cancellation or reduction, first, to the payment in full of any outstanding
Obligations,  and  second,  to the  Company or to such  other  Person who may be
lawfully entitled to receive such funds or as a court of competent  jurisdiction
may direct."

     2.5 Amendment to Section  10.10.  Section 10.10 of the Credit  Agreement is
hereby amended and restated in its entirety to read as follows:

                  10.10    Withholding Tax.

     (a) If any Bank is a "foreign corporation, partnership or trust" within the
meaning of the Code and such Bank claims exemption from, or a reduction of, U.S.
withholding  tax under Sections 1441 or 1442 of the Code,  such Bank agrees with
and in favor of the Agent and the Company, to deliver to the Agent:

     (i)  if such Bank claims an exemption from, or a reduction of,  withholding
tax under a United States tax treaty, two properly completed and executed copies
of IRS Form 1001 before the payment of any interest in the first  calendar  year
and before the payment of any interest in each third  succeeding  calendar  year
during which interest may be paid under this Agreement;

     (ii)  if such Bank claims that interest paid under this Agreement is exempt
from United States  withholding  tax because it is effectively  connected with a
United  States  trade or  business  of such Bank,  two  properly  completed  and
executed  copies of IRS Form 4224 before the  payment of any  interest is due in
the first taxable year of

                                                         2

     such Bank and in each  succeeding  taxable  year of such Bank during  which
interest may be paid under this Agreement; and

     (iii)  to the extent it is legally  able to do so, such other form or forms
as may be  required  under  the Code or other  laws of the  United  States  as a
condition to exemption from, or reduction of, United States withholding tax.

     Such Bank agrees to promptly notify the Agent and the Company of any change
in circumstances  which would modify or render invalid any claimed  exemption or
reduction.

     (b) If any Bank claims  exemption  from, or reduction of,  withholding  tax
under a United States tax treaty by providing IRS Form 1001 and such Bank sells,
assigns,  grants a participation  in, or otherwise  transfers all or part of the
Obligations of the Company to such Bank, such Bank agrees to notify the Agent of
the  percentage  amount  in  which  it is no  longer  the  beneficial  owner  of
Obligations  of the  Company  to such  Bank.  To the  extent of such  percentage
amount, the Agent will treat such Bank's IRS Form 1001 as no longer valid.

     (c) If any Bank claiming  exemption from United States  withholding  tax by
filing IRS Form 4224 with the Agent grants a participation in all or part of the
Obligations  of the Company to such  originating  Bank,  such  originating  Bank
agrees to undertake sole  responsibility  for complying with the withholding tax
requirements  imposed by Sections  1441 and 1442 of the Code with respect to its
participant.

     (d) If any Bank is entitled to a reduction  in the  applicable  withholding
tax,  the Agent may withhold  from any  interest  payment to such Bank an amount
equivalent  to the  applicable  withholding  tax after  taking into account such
reduction.  However, if the forms or other documentation  required by subsection
(a) of this Section are not delivered to the Agent,  then the Agent may withhold
from any  interest  payment  to such  Bank  not  providing  such  forms or other
documentation an amount equivalent to the applicable  withholding tax imposed by
Sections 1441 and 1442 of the Code, without reduction.

     (e) If the IRS or any other Governmental  Authority of the United States or
other  jurisdiction  asserts  a claim  that  the  Agent or the  Company  did not
properly  withhold  tax  from  amounts  paid to or for the  account  of any Bank
(because such Bank failed to notify the Agent of a change in circumstances which
rendered the exemption from, or reduction of,  withholding tax ineffective) such
Bank shall  indemnify  the Agent and the  Company  fully for all  amounts  paid,
directly  or  indirectly,  by the  Agent  or the  Company  as tax or  otherwise,
including  penalties  and  interest,  and  including  any taxes  imposed  by any
jurisdiction  on the amounts  payable to the Agent under this Section,  together
with all costs and expenses  (including  Attorney Costs).  The obligation of the
Banks under this subsection shall survive the payment of all Obligations and the
resignation or replacement of the Agent.


                                                         3

                  2.6      Amendment of Schedules.

     (a) Schedule 2.01 of the Credit Agreement is hereby amended and restated to
read in its entirety as set forth on Schedule 2.01 hereto.

     (b) Schedule  11.02 of the Credit  Agreement is hereby amended and restated
to read in its entirety as set forth on Schedule 11.02 hereto.

                  2.7      Addition of New Bank.

     (a) Upon the date of effectiveness of this Second Amendment (the "Effective
Date"),  the New Bank shall (i) be a party to the Credit Agreement;  (ii) assume
all of the rights and  obligations  of a Bank under the Credit  Agreement with a
Commitment  in the amount set forth  opposite  such Bank's name in Schedule 2.01
attached hereto; and (iii) be secured by the Collateral.  On the Effective Date,
the New Bank shall purchase and assume, and BofA and First Union shall each sell
to the New Bank, 25% of its Commitment under the Credit Agreement, including 25%
of each of the  outstanding  Loans of BofA and First Union (with such  purchase,
assumption  and sale being  deemed to have been  completed  upon  payment of the
purchase price in the manner  referred to below).  As of the date of this Second
Amendment,  there are four outstanding Borrowings of LIBOR Rate Loans, the terms
of which are more particularly  described on Exhibit A hereto. The interest rate
payable by the Company on its outstanding Loans shall not change;  however,  the
interest  rate  distributable  to the  New  Bank  on its  portion  of the  Loans
purchased  from BofA and  First  Union  shall be equal to the LIBOR  Rate for an
Interest  Period of one or three months (as described on Exhibit A),  determined
as of January 15,  1999, plus the Applicable Margin for LIBOR Rate Loans. On the
Effective  Date,  the New Bank shall  assume the  Commitment  of, and pay to the
Agent (for  delivery to BofA and First Union) the  purchase  price for the Loans
sold by, BofA and First Union.  The obligation of the New Bank to so provide its
purchase price to the Agent shall be absolute and unconditional and shall not be
affected by the  occurrence of a Default or Event of Default.  Upon the delivery
by the New Bank to the Agent of the purchase  price due for such Loans,  the New
Bank shall thereupon hold an assignment,  to the extent of such payment,  in the
claim of BofA and First Union against the Company for principal and shall share,
in  accordance  with its Pro Rata Share,  in any  principal  payment made by the
Company with respect to such claim.

     (b) From and after the New Commitment Effective Date, the New Bank shall be
entitled  to its Pro Rata Share of all  interest  and fees  thereafter  accruing
under this Credit Agreement (including, without limitation,  interest on the New
Bank's Pro Rata Share of the  Outstanding  Loans).  All Loans made after the New
Commitment  Effective  Date shall be made by the Banks  pursuant to the Pro Rata
Shares set forth in Schedule 2.01 attached hereto.

     (c) The New Bank hereby (i) warrants and  represents  that it is authorized
to become a party to the Credit  Agreement;  (ii)  appoints and  authorizes  the
Agent to take such

                                                         4

     action,  exercise  such  powers,  and perform  such duties under the Credit
Agreement as are specifically delegated to or required of the Agent by the terms
of the  Credit  Agreement,  together  with such other  powers as are  reasonably
incidental  thereto;  and (iii) agrees that it will abide and be bound by all of
the terms, covenants and agreements,  and perform all of the obligations,  which
by the terms of the Credit  Agreement are required to be abided and performed by
it as a Bank and shall be entitled to all of the rights, benefits and privileges
available or accruing to Banks under the Loan Documents.

     3.  Representations and Warranties.  The Company represents and warrants to
the Agent and the Banks that,  on and as of the date  hereof,  and after  giving
effect to this Second Amendment:

     3.1 Authorization.  The execution,  delivery and performance by the Company
of this Second  Amendment has been duly  authorized  by all necessary  corporate
action,  and this Second  Amendment  has been duly executed and delivered by the
Company.

     3.2 Binding Obligation.  This Second Amendment constitutes the legal, valid
and binding obligation of the Company, enforceable against it in accordance with
its terms,  except as  enforceability  may be limited by applicable  bankruptcy,
insolvency,  or similar laws  affecting the  enforcement  of  creditors'  rights
generally or by equitable principles relating to enforceability.

     3.3 No Legal Obstacle to Amendment. The execution, delivery and performance
of this Second Amendment will not (a) contravene  the Organization  Documents of
the  Company;   (b) constitute   a  breach  or  default  under  any  contractual
restriction or violate or contravene any law or governmental regulation or court
decree or order binding on or affecting the Company which individually or in the
aggregate  does or could  reasonably  be  expected  to have a  Material  Adverse
Effect;  or (c) result in, or require the creation or imposition of, any Lien on
any  of  the  Company's   properties.   No  approval  or  authorization  of  any
governmental  authority  is  required  to  permit  the  execution,  delivery  or
performance  by the  Company  of  this  Second  Amendment,  or the  transactions
contemplated hereby.

     3.4  Incorporation of Certain  Representations.  After giving effect to the
terms of this  Second  Amendment,  the  representations  and  warranties  of the
Company set forth in Article VI of the Credit  Agreement are true and correct in
all  respects  on and as of the date hereof as though made on and as of the date
hereof,  except to the extent such  representations  relate solely to an earlier
specified date.

     3.5 Default.  No Default or Event of Default under the Credit Agreement has
occurred and is continuing.

     4. Conditions,  Effectiveness.  The  effectiveness of this Second Amendment
shall be subject to the  compliance  by the Company with its  agreements  herein
contained, and to the

                                                         5

     delivery of the  following to Agent in form and substance  satisfactory  to
Agent of the following on or before January 31, 1999:

     4.1 Execution of Second Amendment.  The Company, the Agent and the Majority
Banks shall have signed a copy hereof and the same shall have been  delivered to
the Agent.

     4.2  Pledge   Agreement   Affirmations.   The  Agent  shall  have  received
affirmation  letters in respect of the Pledge  Agreement,  substantially  in the
form of Exhibit A, from each Pledgor Subsidiary.

     4.3 Notes.  The Agent shall have received for each of BofA, First Union and
the New Bank, a duly executed Note in the amount of such Bank's Commitment.

     4.4 Other Evidence.  Such other evidence with respect to the Company or any
other person as the Agent,  the New Bank or any Bank may  reasonably  request to
establish the consummation of the transactions  contemplated  hereby, the taking
of all corporate  action in connection with this Second Amendment and the Credit
Agreement and the compliance with the conditions set forth herein.

         5.       Miscellaneous.

     5.1  Effectiveness of the Credit Agreement and the Notes.  Except as hereby
expressly amended,  the Credit Agreement and the Notes shall each remain in full
force and effect,  and are hereby  ratified and confirmed in all respects on and
as of the date hereof.

     5.2  Waivers.  This  Second  Amendment  is  limited  solely to the  matters
expressly  set forth  herein and is  specific in time and in intent and does not
constitute,  nor should it be  construed  as, a waiver or amendment of any other
term or condition, right, power or privilege under the Credit Agreement or under
any agreement,  contract,  indenture,  document or instrument mentioned therein;
nor  does it  preclude  or  prejudice  any  rights  of the  Agent  or the  Banks
thereunder, or any exercise thereof or the exercise of any other right, power or
privilege,  nor shall it require the  Majority  Banks to agree to an  amendment,
waiver or consent for a similar  transaction or on a future occasion,  nor shall
any future waiver of any right, power, privilege or default hereunder,  or under
any  agreement,  contract,  indenture,  document or instrument  mentioned in the
Credit Agreement,  constitute a waiver of any other right,  power,  privilege or
default of the same or of any other term or provision.

     5.3  Counterparts.  This Second  Amendment may be executed in any number of
counterparts,  and all of such  counterparts  taken  together shall be deemed to
constitute one and the same instrument.

     5.4 Governing Law. This Second Amendment shall be governed by and construed
in accordance with the laws of the State of California.

                                                         6


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

                                 SIERRA HEALTH SERVICES, INC.


                                 By:                                       
                                 Name:                                     
                                 Title:                                    


                                 BANK OF AMERICA NATIONAL TRUST AND
                                 SAVINGS ASSOCIATION, as Administrative
                                 Agent


                                 By:                                        
                                 Name:                                      
                                 Title:                                     

                                 BANK OF AMERICA NATIONAL TRUST AND
                                 SAVINGS ASSOCIATION, as a Bank


                                 By:                                        
                                 Name:                                      
                                 Title:                                     


                                 FIRST UNION NATIONAL BANK, as a Bank


                                 By:                                       
                                 Name:                                     
                                 Title:                                    



                                                         7
                               
                                 CREDIT LYONNAIS NEW YORK BRANCH, as


                                 a Bank


                                 By:                                       
                                 Name:                                     
                                 Title:                                    

                                 THE FIRST NATIONAL BANK OF CHICAGO,
                                 as a Bank


                                 By:                                       
                                 Name:                                     
                                 Title:                                    


                                 NORWEST BANK NEVADA N.A., as a BANK
                                 

                                 By: ___________________________________
                                 Name:                                     
                                 Title:                                    


                                 UNION BANK OF CALIFORNIA, N.A., as a
                                 Bank


                                 By:                                        
                                 Name:                                      
                                 Title:                                     



                                                         8

                                 DEUTSCHE BANK AG, NEW YORK AND/OR
                                 CAYMAN ISLANDS BRANCHES, as a New
                                 Bank


                                 By:                           
                                 Name:  _________________________
                                 Title:                                     


                                 By:                                        
                                 Name:                                      
                                 Title:                                     



                                                         9

                                                   SCHEDULE 2.01

                                          COMMITMENTS AND PRO RATA SHARES

<TABLE>

<CAPTION>
Bank                                Commitment                Pro Rata Share

Bank of America National
Trust and Savings
<S>                                <C>                        <C>
Association                        $ 50,000,000               25%

First Union National Bank          $ 40,000,000               20%

Deutsche Bank AG, New York         $ 30,000,000               15%
and/or Cayman Island Branches

Credit Lyonnais
New York Branch                    $ 20,000,000               10%

The First National Bank
of Chicago                         $ 20,000,000               10%

Norwest Bank Nevada N.A.           $ 20,000,000               10%

Union Bank of California, N.A.     $ 20,000,000               10%

                  TOTAL            $200,000,000              100%

</TABLE>


                                                 SCHEDULE 11.02

                                      OFFSHORE AND DOMESTIC LENDING OFFICES,
                                               ADDRESSES FOR NOTICES


BANK OF AMERICA NATIONAL TRUST
AND SAVINGS ASSOCIATION,
         as Administrative Agent

Notices (other than Borrowing Notices and Notices of Conversion/Continuation):

Bank of America National Trust
and Savings Association
Agency Management Services #20529
555 South Flower Street, 11th Floor
Los Angeles, CA 90071

Attention:        Ms. Gina Meador
                  Vice President
                  Telephone: 213/228-5245
                  Facsimile: 213/228-2299

AGENT'S PAYMENT OFFICE:

Notices for Extensions of Credit and Conversion/Continuation:

Bank of America National Trust
and Savings Association
Agency Administrative Services #5596
1850 Gateway Boulevard, Fifth Floor
Concord, CA 94520

Attention:        Kathy Eddy
                  Telephone: 925/675-8458
                  Facsimile: 925/675-8500



BANK OF AMERICA NATIONAL TRUST 
AND SAVINGS ASSOCIATION,
         as a Bank

Domestic and Offshore Lending Office:

GPO-Domestic Account Administration #5583
The Harnor Building, 19th Floor
333 S. Beaudry Ave.
Los Angeles, CA 90017-1486

Attention:        Sandra Ibarra
                  Telephone: 213/345-6536
                  Facsimile: 213/345-6550

Notices (other than Borrowing notices and Notices of Conversion/Continuation):

Bank of America National Trust
and Savings Association
Health Care Finance #9173
555 South Flower Street, 11th Floor
Los Angeles, CA 90071

Attention:        J. Gregory Seibly
                  Vice President
                  Telephone: 213/228-2953
                  Facsimile: 213/228-2756

FIRST UNION NATIONAL BANK

Domestic and Offshore Lending Office:

One First Union Center
Charlotte, North Carolina 28288

Attention:        Sue Patterson
                  Telephone: 704/374-7121
                  Facsimile: 704/374-6537

with a copy of all Notices (other
than Borrowing Notices or Notices
of Conversion/Continuation):



First Union National Bank
One First Union Center
Charlotte, North Carolina 28288

Attention:        Valerie Cline
                  Telephone: 704/383-6237
                  Facsimile: 704/383-9144

DEUTSCHE BANK AG,
New York and/or Cayman Islands Branches

Domestic Lending Office:

Operations:
Richard Agnolet
Deutsche Bank AG
New York Branch
31 W. 52nd Street
New York, NY 10019
Tel: 212-469-4113
Fax: 212-469-4138

Business/Credit Matters
Sue Pearson
Deutsche Bank AG
31 W. 52nd Street
New York, NY 10019
Tel: 212-469-7140
Fax: 212-469-8701

Offshore Lending Office:

Deutsche Bank AG
Cayman Islands Branch
c/o New York Branch

Operations:
Richard Agnolet
Deutsche Bank AG
New York Branch
31 W. 52nd Street
New York, NY 10019
Tel: 212-469-4113
Fax: 212-469-4138

Business/Credit Matters


Sue Pearson
Deutsche Bank AG
31 W. 52nd Street
New York, NY 10019
Tel: 212-469-7140
Fax: 212-469-8701

CREDIT LYONNAIS NEW YORK BRANCH

Domestic and Offshore Lending Office:

1301 Avenue of the Americas
New York, New York 10019

Attention:        Kenia A. Perez
                  Telephone: 212/261-7788
                  Facsimile: 212/261-3440

THE FIRST NATIONAL BANK OF CHICAGO

Domestic and Offshore Lending Office:

One First National Plaza
Chicago, Illinois 60670

Attention:        Ken Fecko
                  Telephone: 312/732-4616
                  Facsimile: 312-732-4303

NORWEST BANK NEVADA N.A.

Domestic and Offshore Lending Office:

3300 West Sahara Avenue
Las Vegas, Nevada 89102

Attention:        Sue Norton
                  Telephone: 702/765-3180
                  Facsimile: 702/765-3888




UNION BANK OF CALIFORNIA, N.A.

Domestic and Offshore Lending Office:


Commercial Customer Service Unit
1980 Saturn Street
Monterey Park, CA 91755

Attention:        Gohar Karapetyan
                  Telephone: 323/720-2679
                  Facsimile: 323/724-6198


                                  EXHIBIT A to
                                Second Amendment
                               to Credit Agreement



                                                 January 15, 1999




Sierra Health Services, Inc.
Sierra Medical Management, Inc.
Prime Holdings, Inc.
c/o Sierra Health Services, Inc.
2724 North Tenaya Way
Las Vegas, Nevada 89128

         Re:      Sierra Health Services, Inc.

Gentlemen:

     Please refer to (1) the Credit Agreement, dated as of October 30,  1998, as
amended by that  certain  First  Amendment  dated as of  November 23,  1998 (the
"Credit Agreement"), by and among Sierra Health Services, Inc., as the Borrower,
the commercial lending institutions party thereto (collectively,  the "Lenders")
and Bank of America National Trust and Savings Association, as agent (herein, in
such  capacity,  called  the  "Agent")  and  (2)  the  Pledge  Agreements  dated
October 30,  1998 from each of the  addressees  in favor of the  Lenders and the
Agent (the "Pledge  Agreements").  Pursuant to an  amendment  dated of even date
herewith,  a copy of which  is  attached  hereto,  certain  terms of the  Credit
Agreement were amended.  We hereby request that you (i) acknowledge and reaffirm
all of your  obligations and  undertakings  under your Pledge Agreement and (ii)
acknowledge  and agree that your Pledge  Agreement  is and shall  remain in full
force and effect in accordance with the terms thereof.

     Please  indicate  your  agreement to the  foregoing by signing in the space
provided below, and returning the executed copy to the undersigned.

                                         BANK OF AMERICA NATIONAL TRUST
                                         AND SAVINGS ASSOCIATION,
                                         as Agent


                                         By:______________________________
                                            Title:






Acknowledged and Agreed to
as of January 15, 1999

SIERRA HEALTH SERVICES, INC.
SIERRA MEDICAL MANAGEMENT, INC.
 

By:____________________________
   Its:___________________________


PRIME HOLDINGS, INC.
 

By:____________________________
   Its:___________________________



                                    EXHIBIT A

                            OUTSTANDING BORROWINGS OF
                                LIBOR RATE LOANS
                            (as of January 15, 1999)







                                                       LENGTH OF INTEREST
BORROWING                                              PERIOD FOR DETERMINING
AMOUNT                  MATURITY                       PAYMENTS TO NEW BANK    

                 
                            
$101,000,000           February 5, 1999                One Month
$ 18,000,000           February 9, 1999                One Month
   8,000,000           February 10, 1999               One Month
$ 12,000,000          March 3, 1999                   Three Months