Exhibit 8.1
                            _______________, 1999


                             FORM OF TAX OPINION


F&M National Corporation                        Security Bank Corporation
9 Court Square                                  8780 Centreville Road
Post Office Box 2800                            Manassas, Virginia 20110
Winchester, Virginia 22604

                  Tax Opinion Relating to the Acquisition of
            Security Bank Corporation by F&M National Corporation

Gentlemen:

      You  have  requested  our  opinion  as  to  certain   federal  income  tax
consequences  of the  proposed  merger of Security Bank Corporation,  a Virginia
chartered banking corporation ("SBC"), with and into F&M Bank-Northern Virginia,
a Virginia  chartered  banking  corporation and  wholly-owned  subsidiary of F&M
National   Corporation   ("F&M"),   pursuant  to  an   Agreement   and  Plan  of
Reorganization,  dated as of  November  25,  1998 and a  related  Plan of Merger
(collectively,  the  "Agreement"),  by and among SBC, F&M and F&M  Bank-Northern
Virginia.

                                  The Merger

      Pursuant to the Agreement and the Plan of Merger (the "Plan")  attached as
Exhibit A to the Agreement,  and subject to various  regulatory  approvals,  SBC
will be merged with and into F&M  Bank-Northern  Virginia in accordance with the
provisions of, and with the effect  provided in, the Virginia Stock  Corporation
Act (the "Merger").  Upon consummation of the Merger, F&M will continue to serve
as the parent  holding  company  for F&M  Bank-Northern  Virginia  and its other
subsidiary  banks,  all of which will  continue to conduct  their  businesses in
substantially the same manner as prior to the Merger.

      At the effective date of the Merger,  and pursuant to the Plan, each share
of common stock of SBC ("SBC Common  Stock") will be exchanged for and converted
into that number of shares of common stock of F&M ("F&M Common Stock") having an
aggregate market value equal to $17.25,  plus cash in lieu of issuing fractional
shares of F&M Common Stock.

                               Our Examination

      In connection with the preparation of this opinion,  we have examined such
documents  concerning the Merger as we have deemed necessary.  We have based our
conclusions  on  the  Internal  Revenue  Code  of  1986  (the  "Code")  and  the
regulations  promulgated pursuant thereto, each as amended from time to time and
in effect as of the date hereof, as well as existing judicial and administrative
interpretations thereof.




      As to various  questions of fact  material to our opinion,  we have relied
upon  the  representations  made in the  Agreement  as  well  as the  additional
representations set forth below. In particular, we have assumed that there is no
plan or  intention on the part of the  shareholders  of SBC to sell or otherwise
dispose of the F&M Common Stock  received by them in the Merger which would have
the effect set forth in paragraph B of the "Additional Representations" below.

                          Additional Representations

      In  connection  with  the  proposed  Merger,   the  following   additional
representations  have been made to and relied upon by us in the  preparation  of
this opinion:

      A. The fair market value of F&M Common Stock received by SBC  shareholders
will be  approximately  equal to the fair market value of SBC Common Stock to be
surrendered in exchange  therefor,  and the exchange ratio used in such exchange
is the result of arm's length negotiations.

      B. To the best  knowledge of the  management  of SBC,  there is no plan or
intention on the part of SBC's  shareholders to sell or otherwise dispose of F&M
Common Stock  received by them in the Merger that will reduce their  holdings of
F&M Common  Stock to a number of shares  having in the  aggregate  a fair market
value of less than 50 percent of the fair market  value of all of the SBC Common
Stock held by SBC shareholders on the effective date of the Merger. For purposes
of this representation, shares of SBC Common Stock exchanged for cash in lieu of
fractional  shares of F&M Common Stock will be treated as outstanding  shares of
SBC Common Stock on the effective date of the Merger. In addition, shares of SBC
Common  Stock and  shares  of F&M  Common  Stock  held by SBC  shareholders  and
otherwise sold, redeemed,  or disposed of prior or subsequent to the Merger will
be considered in making this representation.

      C. F&M has no plan or intention to sell or otherwise dispose of any of the
assets of SBC to be  transferred to F&M in the Merger,  except for  dispositions
made in the  ordinary  course of  business  or  transfers  described  in Section
368(a)(2)(C).

      D. Each party to the Merger will pay its own expenses, if any, incurred in
connection with the Merger.

      E. Following the Merger of SBC with and into F&M  Bank-Northern  Virginia,
F&M will continue the historic business of F&M Bank-Northern Virginia.

      F. F&M has no plan or intention to redeem or reacquire any of its stock to
be issued in the Merger.




      G. The liabilities of SBC to be assumed by F&M Bank-Northern  Virginia as
a result of the Merger and the  liabilities  to which  SBC's  assets are subject
were  incurred in the ordinary  course of business and are  associated  with the
assets to be transferred in the Merger.

      H. There is no  intercorporate  indebtedness  existing between F&M and SBC
that was issued, acquired or will be settled at a discount.

      I. The fair  market  value and  adjusted  basis of the assets of SBC to be
transferred to F&M in the Merger will equal or exceed the sum of the liabilities
assumed  by F&M plus the  amount  of  liabilities  to which the SBC  assets  are
subject.

      J. No  dividends or other  distributions  will be made with respect to any
SBC Common Stock  immediately  before the proposed  Merger,  except for regular,
normal distributions.

      K. None of the  shares of F&M  Common  Stock,  cash in lieu of  fractional
shares or other property received by any shareholder-employee of SBC in exchange
for SBC Common  Stock  pursuant  to the Merger  constitutes  or is  intended  as
compensation for services rendered, or is considered separate consideration for,
or  allocable  to, any  employment  agreement,  warrant,  stock  option or other
relationship.    None   of   the    compensation   to   be   received   by   any
shareholder-employee  of SBC, or warrants or options to acquire F&M Common Stock
which are  exchanged  for  warrants  or options to acquire  SBC Common  Stock in
connection with the Merger, will be separate consideration for, or allocable to,
any  of  such   shareholder-employee's   SBC  Common  Stock.  In  addition,  any
compensation paid to any  shareholder-employee  of SBC,  including any shares of
F&M Common Stock or options or warrants to purchase F&M Common Stock received by
such  shareholder-employee  in exchange for and in cancellation of any option or
warrant to purchase shares of SBC Common Stock existing as of the effective date
of the Merger,  will  constitute  and be intended as  compensation  for services
actually  rendered and bargained for at arm's length,  and will be  commensurate
with  amounts  paid to third  parties  bargaining  at arm's  length for  similar
services.

      L. No two  parties to the Merger are  investment  companies  as defined in
Section  368(a)((2)(F)(iii)  and (iv) of the Code,  and for each of F&M and SBC,
less than 50 percent of the fair  market  value of its total  assets  (excluding
cash,  cash items,  government  securities,  and stock and  securities in any 50
percent or greater subsidiary) consists of stock and securities.

      M. SBC is not under the  jurisdiction  of a court in a Title 11 or similar
case within the meaning of Section 368(a)(3)(A) of the Code.

      N. Cash paid to SBC shareholders in lieu of issuing  fractional  shares of
F&M Common  Stock will be paid  solely for the purpose of saving the expense and
administrative   inconvenience  of  issuing  fractional  shares,   will  not  be
separately  bargained for  consideration  and will  represent  only a mechanical
rounding  off of the  number of shares of F&M  Common  Stock to be issued to SBC
shareholders.




                                 Tax Opinion

      Based upon the foregoing, subject to the limitations expressed herein, and
with due regard to such legal considerations as we deem necessary, we are of the
opinion that for federal income tax purposes:

      1. The Merger will constitute and qualify as a "reorganization" within the
meaning of Section 368(a)(2)(D) of the Code.

      2. No gain,  other income or loss will be  recognized by F&M (Section 1032
of the Code) or SBC (Section 361 of the Code) as a result of the Merger.

      3. To the extent that  shareholders of SBC receive F&M Common Stock solely
in exchange for their shares of SBC Common Stock, they will recognize no gain or
loss as a result of the Merger. Section 354(a)(1) of the Code.

      4. An SBC shareholder  who receives cash in lieu of a fractional  share of
F&M Common Stock will be treated as if the fractional  share of F&M Common Stock
had been issued and then redeemed by F&M. If the deemed redemption  distribution
is not  essentially  equivalent  to a  dividend  within  the  meaning of Section
302(b)(1) of the Code, then the SBC  shareholder  will be treated as receiving a
distribution in redemption of such fractional  share,  subject to the provisions
and  limitations  of  Section  302  of  the  Code.  If  the  deemed   redemption
distribution is essentially  equivalent to a dividend,  then the SBC shareholder
will be treated as receiving a dividend  distribution under Section 301(c)(1) of
the Code, as provided in Section  302(d) of the Code.  See Section  356(a)(2) of
the Code,  as  interpreted  by Clark v.  Commissioner,  489 U.S.  726 (1989) and
Revenue Ruling 66-365, 1966-2 C.B. 116.

      5. The tax basis of F&M Common  Stock  received  by SBC  shareholders  who
exchange their SBC Common Stock for F&M Common Stock will be the same as the tax
basis of SBC Common Stock surrendered in exchange therefor. Section 358(a)(1) of
the Code.

      6. The holding  period of F&M Common  Stock  received by SBC  shareholders
will include the period  during which SBC Common Stock  surrendered  in exchange
therefor  was held by such SBC  shareholders,  provided the SBC Common Stock was
held as a capital  asset on the date of the  exchange.  Section  1223(1)  of the
Code.

      This opinion is based upon the  provisions of the Code, as  interpreted by
regulations,  administrative  rulings,  and case  law,  in effect as of the date
hereof.

      This  opinion is  provided  in  connection  with the Merger as required by
Section 5.1(d) of the  Agreement,  is solely for the benefit of F&M, SBC and SBC
shareholders, and may not be








relied upon in any other manner or by any other person.  This opinion may not be
disclosed  to any other  person or used in any other  manner  without  the prior
written consent of the undersigned.

                                    Very truly yours,



                                    LECLAIR RYAN,
                                    A Professional Corporation