SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

             Information Statement Pursuant to Rules 13d-1 and 13d-2
                    Under the Securities Exchange Act of 1934
                               (Amendment No. 13)*

                          Sierra Health Services, Inc.
                                (Name of Issuer)

                                  Common Stock
                         (Title of Class of Securities)

                                   826322-109
                                 (CUSIP Number)



*The  remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for  any  subsequent   amendment   containing   information  which  would  alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).





                                  SCHEDULE 13G

CUSIP No. 826322-109

1  NAME OF REPORTING PERSON
    S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

         Anthony M. Marlon, M.D.
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2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*          (A) |_|
                                                              (B) |_|

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3  SEC USE ONLY

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4  CITIZENSHIP OR PLACE OF ORGANIZATION
         United States of America

                          5   SOLE VOTING POWER
   NUMBER OF                   2,472,196 shares of Common Stock at 12/31/00
     SHARES

  BENEFICIALLY            6    SHARED VOTING POWER
    OWNED BY                    -0- at 12/31/00
      EACH

    REPORTING             7   SOLE DISPOSITIVE POWER
     PERSON                    2,472,196 shares of Common Stock at 12/31/00
      WITH

                          8   SHARED DISPOSITIVE POWER
                               -0- at 12/31/00

9   AGGREGATE  AMOUNT  BENEFICIALLY  OWNED  BY  EACH  REPORTING PERSON
         2,472,196 shares of Common Stock at 12/31/00

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10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
        CERTAIN  SHARES* |X|    See Item 4 of attached Schedule 13G
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11   PERCENT OF CLASS  REPRESENTED  BY AMOUNT IN ROW (9)
        9.0% of outstanding class at 12/31/00
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12   TYPE OF REPORTING PERSON*
         IN

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                      *SEE INSTRUCTIONS BEFORE FILLING OUT!





Item 1.   (a)      Name of Issuer:

                   Sierra Health Services, Inc.

          (b)      Address of Issuer's Principal Executive Offices:

                   2724 North Tenaya Way
                   Las Vegas, Nevada  89128

Item 2.   (a)      Name of Person Filing:

                   Anthony M. Marlon, M.D.  ("Dr. Marlon")

          (b)      Address of Principal Business Office or, if none, Residence:

                   2724 North Tenaya Way
                   Las Vegas, Nevada  89128

          (c)      Citizenship:

                   United States of America

          (d)      Title of Class of Securities:

                   Common Stock, $.005 par value

          (e)      CUSIP Number:

                   826322-109

Item 3.   This statement is filed  pursuant to Rule 13d-1(c).
          Items 3(a) through 3(h) are, therefore, inapplicable.

Item 4.   Ownership

          (a)      Amount Beneficially Owned:






                           Dr.  Marlon  may  be  deemed  to   beneficially   own
                           2,472,196  shares of  Common  Stock at  December  31,
                           2000.  That number of shares reported as beneficially
                           owned  includes   2,329,003  shares  held  indirectly
                           through  a total of four  trusts  established  by Dr.
                           Marlon and his wife, and 1,500 shares held indirectly
                           through a limited  partnership  (the  "Partnership").
                           Dr.  Marlon  may be  deemed  to have or share  voting
                           power and/or  dispositive  power over the shares held
                           by the four trusts and, therefore, to have beneficial
                           ownership with respect to such shares. Dr. Marlon, as
                           managing general partner of the Partnership, has sole
                           voting and dispositive  power over the shares held by
                           the  Partnership.  Dr.  Marlon  disclaims  beneficial
                           ownership  as to the shares held by the four  trusts,
                           other than the  1,135,341  shares  held by the Marlon
                           Family  Trust  (a  revocable  trust  of which he is a
                           trustee).   The   number   of  shares   reported   as
                           beneficially  owned also includes  65,000 shares that
                           Dr.  Marlon has a right to acquire  within 60 days of
                           December  31,  2000,  upon  exercise of options,  and
                           includes 76,693 shares held for Dr. Marlon's  account
                           under the Company's  401(k) plan for  employees.  Dr.
                           Marlon's   beneficial   ownership  does  not  include
                           163,054  shares held in three  trusts for the benefit
                           of family  members,  the  trustee of each of which is
                           Erin E.  MacDonald,  and  does  not  include  652,648
                           shares   held  by  the  AMM  &  RM   Family   Limited
                           Partnership,  the general partner of which is a trust
                           for the benefit of a family  member;  the trustees of
                           that trust are Ms.  MacDonald,  William Godfrey,  and
                           Jeannine  M. Zeller  (daughter  of Dr.  Marlon).  Dr.
                           Marlon's  beneficial  ownership also does not include
                           445,000 shares subject to stock options which are not
                           currently exercisable and will not become exercisable
                           within 60 days after December 31, 2000.

         (b)      Percent of Class:

                  9.0% of the class of Common Stock outstanding at
                  December 31, 2000

         (c)      Number of shares as to which Dr. Marlon has:

                  (i)  sole power to vote or to direct the vote:
                         2,472,196 shares of Common Stock at December
                         31, 2000 (see Item 4(a) above.)

                  (ii)  shared power to vote or to direct the vote:
                          -0- shares of Common Stock at December 31, 2000

                  (iii)  sole power to dispose or to direct the disposition of:
                           2,472,196 shares of Common Stock at December
                           31, 2000 (see Item 4(a) above.)

                  (iv)  shared power to dispose or to direct the disposition of:
                           -0- shares of Common Stock at December 31, 2000

Item 5.    Ownership of Five Percent or Less of a Class

           Not applicable.

Item 6.    Ownership of More than Five Percent on Behalf of Another Person

           Not applicable.






Item 7.    Identification and Classification of the Subsidiary Which Acquired
           the Security Being Reported on By the Parent Holding Company

           Not applicable.

Item 8.    Identification and Classification of Members of the Group

           Not applicable.

Item 9.    Notice of Dissolution of Group

           Not applicable.

Item 10.   Certification.

           Not  applicable.  This  statement  is filed  pursuant  to Rule
13d-1(c).

         The filing of this Amendment to Schedule 13G and amendments hereto, and
the statements  herein and therein,  shall not be construed as an admission that
any filing  person or any other  person named herein is, for purposes of Section
13(d),  13(g), 16(a), or 16(b) under the Exchange Act, or for any other purpose,
the  beneficial  owner of any of the  securities  described  herein or  therein,
except to the extent  that a natural  person is  reported  as having  voting and
dispositive power, and thus beneficial  ownership for purposes of Sections 13(d)
and 13(g), over securities owned directly by such person.

                                   SIGNATURES

         After reasonable  inquiry and to the best of my knowledge and belief, I
certify that the information  set forth in this statement is true,  complete and
correct.

February 12, 2001

         Date

/s/ Anthony M. Marlon, M.D.
---------------------------
ANTHONY M. MARLON, M.D.
      Name/Title