AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON NOVEMBER 12, 2004
                                                  REGISTRATION NO. 333 - 61200


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    

                         POST-EFFECTIVE AMENDMENT NO. 7
                                       TO
                                    FORM S-3
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                        

                                ESSEX CORPORATION
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

COMMONWEALTH OF VIRGINIA                                             54-0846569
(STATE OR OTHER JURISDICTION OF                 (I.R.S. EMPLOYER IDENTIFICATION
 INCORPORATION OR ORGANIZATION)                                         NUMBER)
                                
                               9150 GUILFORD ROAD
                            COLUMBIA, MARYLAND 21046
                                 (301) 939-7000
                   (ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE
                         NUMBER, INCLUDING AREA CODE, OF
                        REGISTRANT'S PRINCIPAL EXECUTIVE
                                    OFFICES)

                              LEONARD E. MOODISPAW
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                ESSEX CORPORATION
                               9150 GUILFORD ROAD
                            COLUMBIA, MARYLAND 21046

                                   COPIES TO:
                                 JOHN R. HEMPILL
                             MORRISON & FOERSTER LLP
                           1290 AVENUE OF THE AMERICAN
                            NEW YORK, NEW YORK 10104
                                 (212) 468-8082
 (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE,
  OF AGENT FOR SERVICE)
                                    
         APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO PUBLIC: As soon as
practicable after the effective date of this Registration Statement.
         If the only securities  being registered on this form are being offered
pursuant to dividend or interest  reinvestment plans, please check the following
box. / /
         If any of the  securities  being  registered  on  this  form  are to be
offered  on a  delayed  or  continuous  basis  pursuant  to Rule 415  under  the
Securities Act of 1933,  other than  securities  offered only in connection with
dividend or interest reinvestment plans, check the following box. /X/
         If this form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list  the  Securities  Act  registration  statement  number  of the  earlier
effective registration statement for the same offering. / /
         If this  form is a  post-effective  amendment  filed  pursuant  to Rule
462(c) under the Securities Act, check the following box and list the Securities
Act  registration   statement  number  of  the  earlier  effective  registration
statement for the same offering. / /
         If delivery of the  prospectus  is expected to be made pursuant to Rule
434, please check the following box. / /

         THE REGISTRANT HEREBY AMENDS THIS  REGISTRATION  STATEMENT ON SUCH DATE
OR DATES AS MAY BE NECESSARY TO DELAY ITS  EFFECTIVE  DATE UNTIL THE  REGISTRANT
SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY  STATES THAT THIS REGISTRATION
STATEMENT SHALL  THEREAFTER  BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE  SECURITIES  ACT OF 1933, AS AMENDED,  OR UNTIL THE  REGISTRATION  STATEMENT
SHALL BECOME  EFFECTIVE ON SUCH DATE AS THE COMMISSION,  ACTING PURSUANT TO SAID
SECTION 8(A), MAY DETERMINE.






                               INTRODUCTORY NOTE

         THIS  POST-EFFECTIVE  AMENDMENT  NO. 7 TO FORM S-3  REMOVES  FROM  THIS
REGISTRATION  STATEMENT AND DEREGISTERS  330,000 SHARES OF COMMON STOCK OF ESSEX
CORPORATION  (THE "COMPANY")  HELD BY GLOBAL  ENVIRONMENT  STRATEGIC  TECHNOLOGY
PARTNERS,  LP THAT HAVE BEEN INCLUDED FOR REGISTRATION IN AMENDMENT NO. 1 TO THE
FORM S-3 REGISTRATION  STATEMENT (FILE NO.  333-120137)  FILED BY THE COMPANY ON
NOVEMBER 9, 2004.







                                   SIGNATURES

         Pursuant to the  requirements of the Securities Act, the Registrant has
duly caused this Post Effective Amendment No. 7 to the Registration Statement to
be signed on its behalf by the undersigned,  thereunto duly  authorized,  in the
County of Howard, State of Maryland, on November 12, 2004.

         SIGNATURE                                          TITLE
       ------------                                        -------
             *
----------------------------
     H. JEFFREY LEONARD              Chairman of the Board

   s/ LEONARD E. MOODISPAW       
----------------------------         President, Chief Executive Officer, and
    LEONARD E. MOODISPAW             Director (principal executive officer)

    /s/ LISA G. JACOBSON         
----------------------------         Executive Vice President, Chief Financial
      LISA G. JACOBSON               Officer (principal financial officer and
                                     principal accounting officer)

                                 
----------------------------
       JOHN G. HANNON                Director

             *                   
----------------------------
      ROBERT W. HICKS                Director

             *                   
----------------------------
       RAY M. KEELER                 Director

----------------------------
     ANTHONY M. JOHNSON              Director

             *                   
----------------------------
      MARIE S. MINTON                Director

                                 
----------------------------
      ARTHUR L. MONEY                Director

             *                   
----------------------------
      TERRY M. TURPIN                Director


                                            *By:  /S/ LEONARD E. MOODISPAW
                                                  ------------------------
                                                     LEONARD E. MOODISPAW
                                                     ATTORNEY-IN-FACT

o       Pursuant  to a power of  attorney  dated  May 17,  2001  filed  with the
        Registration Statement (No. 333-61200)