UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    FORM 10-K

[X]      Annual  report  pursuant  to  Section  13 or  15(d)  of the Securities
         Exchange Act of 1934 for the fiscal period December 31, 2005

[ ]      Transition report pursuant to Section 13 or 15(d) of the
         Securities Exchange Act of 1934 for the transition period from   to


                                        Commission File Number 333-121990-03

                       J.P.MORGAN ACCEPTANCE CORPORATION I
             (Exact name of registrant as specified in its charter)


         Delaware                                           13-3475488
State or other jurisdiction of                           (I.R.S. Employer
incorporation or organization                            Identification No.)

270 Park Avenue
New York, New York                                             10017
(Address of Principal Executive Offices)                     (Zip Code)

       Registrant's telephone number, including area code :(212) 270-8863

                J.P. Morgan Mortgage Acquisition Corp. 2005-OPT1
            Asset Backed Pass-Through Certificates, Series 2005-OPT1
                                (Issuing Entity)

                      J.P. Morgan Acceptance Corporation I
             (Exact name of Depositor as specified in its charter)

                     J.P. Morgan Mortgage Acquisition Corp.
              (Exact name of Sponsor as specified in its charter)


Securities registered pursuant to Section 12(b) of the Act: None

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as
defined in Rule 405 of the Securities Act.  Yes [ ]  No [X]

Indicate by check mark if the registrant is not required to file reports
pursuant to Section 13 or Section 15(d) of the Act.  Yes [  ]   No [X]

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months (or for such  shorter  period that the  registrant  was
required  to file  such  reports),  and  (2) has  been  subject  to such  filing
requirements for the past 90 days. Yes [X] No [ ]

Indicate by check mark if disclosure of delinquent  filers  pursuant to Item 405
of Regulation  S-K (229.405 of this chapter) is not contained  herein,  and will
not be contained,  to the best of registrant's knowledge, in definitive proxy or
information  statements  incorporated by reference in Part III of this Form 10-K
or any amendment to this Form 10-K. [X]

Indicate by check mark whether the registrant is a large  accelerated  filer, an
accelerated  filer, or a  non-accelerated  filer. See definition of "accelerated
filer and large accelerated filer" in Rule 12-b-2 of the Exchange Act.

Large accelerated filer [ ]   Accelerated filer [ ]   Non-accelerated filer [X]

Indicate by check mark whether the  registrant is a shell company (as defined in
Exchange Act Rule 12b-2).    Yes  No [X]

State the aggregate market value of the voting and non-voting common equity held
by non-affiliates  computed by reference to the price at which the common equity
was last sold, or the average bid and asked price of such common  equity,  as of
the last business day of the registrant's most recently  completed second fiscal
quarter.   Not Applicable.

Indicate the number of shares outstanding of each of the registrant's
classes of common stock, as of the latest practicable date.  Not Applicable.

Documents incorporated by reference:  None


<PAGE>

PART I

Item 1.  Business.

         Not Applicable.

Item 1A. Risk Factors.

         Not Applicable.

Item 1B. Unresolved Staff Comments.

         None.

Item 2.  Properties.

         Not Applicable.

Item 3.  Legal Proceedings.

         The  Registrant   knows  of  no  material  pending  legal   proceedings
         involving the trust created under the Pooling  and Servicing Agreement,
         the Trustee,  any Servicer or  the Registrant with respect to the trust
         other  than  routine  litigation  incidental  to   the  duties  of  the
         respective parties.

Item 4.  Submission of Matters to a Vote of Security Holders

         None.

PART II

Item 5.  Market for Registrant's Common Equity,  Related Stockholder Matters and
         Issuer Purchases of Equity Securities.

         Currently,   there  is   no  established   secondary   market  for  the
         Certificates  known to  the  Registrant.  As of December 31, 2005,  the
         number of holders  of each class of offered  certificates  was 55 based
         on  records provided by DTC.

Item 6.  Selected Financial Data

         Not Applicable.

Item 7.  Management's Discussion and Analysis of Financial condition and
         Results of Operation.

         Not Applicable.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

         Not Applicable.

Item 8.  Financial Statements and Supplementary Data.

         Not Applicable.

Item 9.  Changes in and Disagreements with Accountants on Accounting and
         Financial Disclosure.

         None.

Item 9A. Controls and Procedures.

         Not Applicable.

Item 9B. Other Information.

         Not Applicable.


                                      -2-

<PAGE>

PART III

Item 10. Directors and Executive Officers of the Registrant.

         Not Applicable.

Item 11. Executive Compensation.

         Not Applicable.

Item 12. Security Ownership of Certain Beneficial Owners and Management and
         Related Stockholder Matters.

         Not Applicable.

Item 13. Certain Relationships and Related Transactions.

         No reportable transactions have occurred.

Item 14. Principal Accounting Fees and Services.

         Not Applicable.

PART IV


Item 15. Exhibits, Financial Statement Schedules.

(a) The following documents are filed as part of this report:

    (1)  Financial Statements:

         Not Applicable.

    (2)  Financial Statement Schedules:

         Not Applicable.

    (3)  Exhibits:

         Rule 13a-14(a)/15d-14(a) Certification, filed as 31.1 hereto.

         Annual Independent Accountant's Servicing Report concerning servicing
         activities, filed as Exhibit 99.1 hereto.

         Report of Management as to Compliance with Minimum Servicing Standards,
         filed as Exhibit 99.2 herto.

         Annual Statement as to Compliance, filed as Exhibit 99.3 herto.

         Aggregate Statement of Principal and Interest Distributions to
         Certificateholders as of December 31, 2005, filed as Exhibit 99.4
         hereto.

(b) Exhibits to this report are listed in Item (15)(a)(3)above.

(c) Not Applicable.

                                      -3-
<PAGE>


SIGNATURE

Pursuant to the  requirements of Section 13 or 15(d) of the Securities  Exchange
Act of 1934,  the  registrant  has duly  caused  this report to be signed on its
behalf by the undersigned thereunto duly authorized.


               By: /s/ Brian Bernard
                    -----------------------------
             Name:  Brian Bernard
            Title:  President
             Date:  March 31, 2006




                                      -4-
<PAGE>




SUPPLEMENTAL  INFORMATION TO BE FURNISHED WITH REPORTS FILED PURSUANT TO SECTION
15(D) OF THE ACT BY REGISTRANTS WHICH HAVE NOT REGISTERED SECURITIES PURSUANT TO
SECTION 12 OF THE ACT.

The  registrant  has not sent an annual report or proxy material to its security
holders.  The registrant  will not be sending an annual report or proxy material
to its security holders subsequent to the filing of this form.

                                      -5-
<PAGE>



                                 EXHIBIT INDEX

Exhibit   Description

31.1      Rule 13a-14(a)/15d-14(a) Certification

99.1      Annual Independent Accountant's Servicing Report

99.2      Report of Management as to Compliance with Minimum Servicing Standards

99.3      Annual Statement as to Compliance

99.4      Aggregate Statement of Principal and Interest Distributions to
          Certificateholders as of December 31, 2005



                                      -6-

<page>

                                  Exhibit 31.1
                     Rule 13a-14(a)/15d-14(a) Certification

                      J.P. Morgan Acceptance Corporation I,
                     J.P. Morgan Mortgage Acquisition Corp.,
            Asset-Backed Pass-Through Certificates, Series 2005-OPT1

     I, Brian Bernard, the President of the Depositor, certify that:

1.   I have reviewed  this annual  report on Form 10-K,  and all reports on Form
     8-K  containing  distribution  and  servicing  reports  filed in respect of
     periods included in the year covered by this annual report,  of J.P. Morgan
     Acquisition Corp. 2005-OPT1 (the "Trust");

2.   Based on my knowledge,  the information in these reports, taken as a whole,
     does not contain any untrue statement of a material fact or omit to state a
     material  fact  necessary  to make  the  statements  made,  in light of the
     circumstances  under which such  statements were made, not misleading as of
     the last day of the period covered by this annual report;

3.   Based on my knowledge, the distribution information required to be prepared
     by the  Securities  Administrator  based  upon  the  servicing  information
     required  to be provided by the  Servicer  under the Pooling and  Servicing
     Agreement is included in these reports;

4.   Based on my knowledge and upon the annual compliance statements included in
     the report and required to be delivered to the Securities  Administrator in
     accordance with the terms of the Pooling and Servicing  Agreement and based
     upon the review  required  under the Pooling and Servicing  Agreement,  and
     except  as  disclosed  in  the  report,  the  Servicer  has  fulfilled  its
     obligations under the Pooling and Servicing Agreement; and

5.   The  reports  disclose  all  significant   deficiencies   relating  to  the
     Servicer's  compliance with the minimum servicing  standards based, in each
     case, upon the report provided by an independent public  accountant,  after
     conducting  a review in  compliance  with the  Uniform  Single  Attestation
     Program  for  Mortgage  Bankers  or  similar  standard  as set forth in the
     Pooling and Servicing Agreement, that is included in these reports.

     In  giving  the  certifications  above,  I have  reasonably  relied  on the
information provided to me by the following unaffiliated  parties: the Servicer.

     Capitalized terms used but not defined herein have the meanings ascribed to
them in the  Pooling and  Servicing  Agreement,  dated July 1, 2005,  among J.P.
Morgan Acceptance Corporation I, as depositor,  J.P. Morgan Mortgage Acquisition
Corp., as seller (the "Seller"),  JPMorgan Chase Bank, National Association,  as
securities administrator (the "Securities  Administrator"),  Option One Mortgage
Corporation as servicer (the "Servicer"), and U.S. Bank National Association, as
trustee (the "Trustee").

   By: /s/ Brian Bernard
       -------------------------------------
 Name:  Brian Bernard
Title:  President

Dated:  March 31, 2006

                                      -7-

<page>


                                  EXHIBIT 99.1
                Annual Independent Accountant's Servicing Report


KPMG LLP
Suite 2000
355 South Grand Avenue
Los Angeles, CA  90071


                        Independent Accountants' Report


To the Board of Directors and Stockholder
of Option One Mortgage Corporation

We have examined management's assertion, included in the accompanying management
assertion,  that  Option One  Mortgage  Corporation  complied  with the  minimum
servicing  standards set forth in the Mortgage Bankers  Association of America's
Uniform Single  Attestation  Program for Mortgage Bankers as of and for the year
ended  December  31, 2005.  Management  is  responsible  for Option One Mortgage
Corporation's   compliance   with  those  minimum   servicing   standards.   Our
responsibility  is to express an opinion  on  management's  assertion  about the
Company's compliance based on our examination.

Our examination was conducted in accordance with attestion standards established
by the American  Institute of Certified  Public  Accountants  and,  accordingly,
included  examining,  on a test basis,  evidence  about the Option One  Mortgage
Corporation's  compliance with the minimum servicing  standards  specified above
and  performing  other  such  procedures  as  we  considered  necessary  in  the
circumstances.  We believe that our examination  provides a reasonable basis for
our opinion.  Our examination  does not provide a legal  determination on Option
One Mortgage Corporation's compliance with the minimum servicing standards.

In our opinion,  management's  assertion  that Option One  Mortgage  Corporation
complied with the aforementioned  minimum servicing  standards as of and for the
year ended December 31, 2005 is fairly stated, in all material respects.


/s/ KPMG LLP
------------------------------------
Los Angeles, California
February 28, 2006

                                      -8-
<page>

                                  EXHIBIT 99.2
     Report of Management as to Compliance with Minimum Servicing Standards
                              -------------------

OPTION ONE MORTGAGE

                             Management's Assertion


As of and for the year ended December 31, 2005, Option One Mortgage  Corporation
complied in all material respects with the minimum servicing standards set forth
in the Mortgage  Bankers  Association of America's  Uniform  Single  Attestation
Program  for  Mortgage  Bankers.  As of and for this  same  period,  Option  One
Mortgage  Corporation  had in effect a fidelity  bond and  errors and  omissions
policy in the amounts of $70,000,000 and $10,000,000, respectively.

/s/ Robert E. Dubrish
----------------------------------------------
Robert E. Dubrish, Chief Executive Officer


/s/ William L. O'Neill
-----------------------------------------------
William L. O'Neill, Chief Financial Officer


/s/ Matthew A. Engel
-----------------------------------------------
Matthew A. Engel, Controller


/s/ Fabiola Camperi
-----------------------------------------------
Fabiola Camperi, Chief Servicing Officer

                                      -9-
<page>


                                  EXHIBIT 99.3
                       Annual Statement as to Compliance
                                 --------------


                             OFFICER'S CERTIFICATE

                        ANNUAL STATEMENT OF THE SERVICER

     I, Fabiola  Camperi,  the duly appointed Chief Servicing  Officer of Option
One Mortgage Corporation,  the Servicer, hereby certify that (i) a review of the
activities of the Servicer  during the calendar year ended December 31, 2005 and
of performance  under the Servicing  Agreement,  as defined in the cover letter,
has been made under the supervision, and (ii) to the best of my knowledge, based
on such review,  the Servicer has  fulfilled  all of its  obligations  under the
Servicing Agreement during such year.

By:  /s/ Fabiola Camperi
     -------------------------
Name:   Fabiola Camperi
Title:  Chief Servicing Officer
Date:   February 28, 2006


                                      -10-
<PAGE>

                                  EXHIBIT 99.4
         Aggregate Statement of Principal and Interest Distributions to
                   Certificateholders as of December 31, 2005
                                 --------------

<table>

       <c>       <c>

---------------------------------------------------------------------------------------------------------------------------------
  CUSIP        ORIGINAL              PAID            PAID               TOTAL PAID             ENDING PRIN      CERT POOL FACTOR
              PRINCIPAL            PRINCIPAL        INTEREST                                     BALANCE           (Per 1000)
---------------------------------------------------------------------------------------------------------------------------------
46626LAA8     612,849,000.00   116,996,048.25      11,951,128.00       128,947,176.25         495,852,951.75       809.09482067
46626LAB6     223,140,000.00   134,543,993.27       3,476,500.91       138,020,494.18          88,596,006.73       397.04224581
46626LAC4     303,284,000.00                -       6,370,638.38         6,370,638.38         303,284,000.00     1,000.00000000
46626LAD2      40,111,000.00                -         871,098.10           871,098.10          40,111,000.00     1,000.00000000
46626LAE0      60,404,000.00                -       1,342,510.36         1,342,510.36          60,404,000.00     1,000.00000000
46626LAF7      46,813,000.00                -       1,045,202.63         1,045,202.63          46,813,000.00     1,000.00000000
46626LAG5      29,447,000.00                -         661,959.36           661,959.36          29,447,000.00     1,000.00000000
46626LAH3      27,182,000.00                -         627,623.88           627,623.88          27,182,000.00     1,000.00000000
46626LAJ9      24,917,000.00                -         577,858.97           577,858.97          24,917,000.00     1,000.00000000
46626LAK6      23,406,000.00                -         551,145.46           551,145.46          23,406,000.00     1,000.00000000
46626LAL4      21,141,000.00                -         553,693.80           553,693.80          21,141,000.00     1,000.00000000
46626LAM2      18,876,000.00                -         510,684.29           510,684.29          18,876,000.00     1,000.00000000
46626LAN0      15,101,000.00                -         443,096.37           443,096.37          15,101,000.00     1,000.00000000
46626LAP5      15,101,000.00                -         531,374.31           531,374.31          15,101,000.00     1,000.00000000
U48118AA8               0.01                -                  -                    -                   0.01     1,000.00000000
N/C120676   1,510,095,312.15                -      20,008,591.40        20,008,591.40       1,510,095,312.15     1,000.00000000
N/C120677             100.00                -       3,439,649.88         3,439,649.88                 100.00     1,000.00000000
N/C120678                  -                -                  -                    -                      -     1,000.00000000
---------------------------------------------------------------------------------------------------------------------------------

 </TABLE>
                                      -11-