As filed with the Securities and Exchange Commission on October 23, 2006

                                            Securities Act File No. 333-130530
                                      Investment Company Act File No. 811-4375

==============================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549
                               -----------------

                                   FORM N-14
                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933
                               -----------------

                          Pre-Effective Amendment No.
                        Post-Effective Amendment No. 1

                               -----------------

                 BLACKROCK MULTI-STATE MUNICIPAL SERIES TRUST
              (Exact name of Registrant as Specified in Charter)
                               -----------------
                                (609) 282-2800
                       (Area Code and Telephone Number)

                               -----------------

                            800 Scudders Mill Road
                         Plainsboro, New Jersey 08536

                   (Address of Principal Executive Offices:
                    Number, Street, City, State, Zip Code)

                               -----------------

                              Robert C. Doll, Jr.
                 BlackRock Multi-State Municipal Series Trust
             800 Scudders Mill Road, Plainsboro, New Jersey 08536
       Mailing Address: P.O. Box 9011, Princeton, New Jersey 08543-9011

                    (Name and Address of Agent for Service)

                                  copies to:



                                                    
   Frank P. Bruno, Esq.        Brian Kindelan, Esq.                 David C. Phelan, Esq.
    Sidley Austin LLP        BlackRock Advisors, LLC      Wilmer Cutler Pickering Hale and Dorr LLP
   787 Seventh Avenue          100 Bellevue Parkway                    60 State Street
New York, New York 10019    Wilmington, Delaware 19809          Boston, Massachusetts 02109


                               -----------------

     No filing fee is required because of reliance on Section 24(f) of the
                        Investment Company Act of 1940.



      This Post-Effective Amendment No. 1 to the Registrant's Registration
Statement on Form N-14 (File No. 333-130530) (the "N-14 Registration
Statement") consists of the following:

      (1) Facing Sheet of this Registration Statement

      (2) Part C of this Registration Statement (including signature page).

      Parts A and B to the N-14 Registration Statement are unchanged from the
Proxy Statement and Prospectus filed on February 3, 2006 contained in
Pre-Effective Amendment No. 3 to the Fund's N-14 Registration Statement.

      This Post-Effective Amendment No. 1 to the N-14 Registration Statement
is being filed solely to file a tax opinion of Sidley Austin LLP, counsel for
the Registrant, as Exhibit 12 to the N-14 Registration Statement. The tax
opinion relates to the reorganization of Lebenthal New Jersey Municipal Bond
Fund, a series of Lebenthal Funds, Inc., into BlackRock New Jersey Municipal
Bond Fund (formerly known as Merrill Lynch New Jersey Municipal Bond Fund), a
series of the Registrant.




                                    PART C

                               OTHER INFORMATION

Item 15. Indemnification.

Section 5.3 of the Registrant's Declaration of Trust provides as follows:

      "The Trust shall indemnify each of its Trustees, officers, employees and
agents (including persons who serve at its request as directors, officers or
trustees of another organization in which it has any interest as a
shareholder, creditor or otherwise) against all liabilities and expenses
(including amounts paid in satisfaction of judgments, in compromise, as fines
and penalties and as counsel fees) reasonably incurred by him in connection
with the defense or disposition of any action, suit or other proceeding,
whether civil or criminal, in which he may be involved or with which he may be
threatened, while in office or thereafter, by reason of his being or having
been such a trustee, officer, employee or agent, except with respect to any
matter as to which he shall have been adjudicated to have acted in bad faith,
willful misfeasance, gross negligence or reckless disregard of his duties;
provided, however, that as to any matter disposed of by a compromise payment
by such person, pursuant to a consent decree or otherwise, no indemnification
either for said payment or for any other expenses shall be provided unless the
Trust shall have received a written opinion from independent legal counsel
approved by the Trustees to the effect that if either the matter of willful
misfeasance, gross negligence or reckless disregard of duty, or the matter of
good faith and reasonable belief as to the best interests of the Trust, had
been adjudicated, it would have been adjudicated in favor of such person. The
rights accruing to any Person under these provisions shall not exclude any
other right to which he or she may be lawfully entitled; provided that no
Person may satisfy any right in indemnity of reimbursement granted herein or
in Section 5.1 or to which he or she may be otherwise entitled except out of
the property of the Trust, and no Shareholder shall be personally liable to
any Person with respect to any claim for indemnity or reimbursement or
otherwise. The Trustees may make advance payments in connection with
indemnification under this Section 5.3, provided that the indemnified person
shall have given a written undertaking to reimburse the Trust in the event it
is subsequently determined that he is not entitled to such indemnification."

      Insofar as the conditional advancing of indemnification moneys for
actions based upon the Investment Company Act of 1940, as amended (the
"Investment Company Act"), may be concerned, such payments will be made only
on the following conditions: (i) the advances must be limited to amounts used,
or to be used, for the preparation or presentation of a defense to the action,
including costs connected with the preparation of a settlement; (ii) advances
may be made only upon receipt of a written promise by, or on behalf of, the
recipient to repay that amount of the advance which exceeds the amount which
it is ultimately determined that he or she is entitled to receive from the
Registrant by reason of indemnification; and (iii)(a) such promise must be
secured by a surety bond, other suitable insurance or an equivalent form of
security which assures that any repayments may be obtained by the Registrant
without delay or litigation, which bond, insurance or other form of security
must be provided by the recipient of the advance, or (b) a majority of a
quorum of the Registrant's disinterested, non-party Trustees, or an
independent legal counsel in a written opinion, shall determine, based upon a
review of readily available facts that the recipient of the advance ultimately
will be found entitled to indemnification.

      In Section 9 of each Distribution Agreement relating to the securities
being offered hereby, the Registrant agrees to indemnify the Distributor and
each person, if any, who controls the Distributor within the meaning of the
Securities Act of 1933, as amended ("1933 Act"), against certain types of
civil liabilities arising in connection with the Registration Statement or
Prospectus and Statement of Additional Information.

      Insofar as indemnification for liabilities arising under the 1933 Act
may be permitted to Trustees, officers and controlling persons of the
Registrant and the principal underwriter pursuant to the foregoing provisions
or otherwise, the Registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public
policy as expressed in the 1933 Act and is, therefore, unenforceable. In the
event that a claim for indemnification against such liabilities (other than
the payment by the Registrant of expenses incurred or paid by a Trustee,
officer, or controlling person of the Registrant and the principal underwriter
in



                                     C-1


connection with the successful defense of any action, suit or proceeding) is
asserted by such Trustee, officer or controlling person or the principal
underwriter in connection with the shares being registered, the Registrant
will, unless in the opinion of its counsel the matter has been settled by
controlling precedent, submit to a court of appropriate jurisdiction the
question whether such indemnification by it is against public policy as
expressed in the 1933 Act and will be governed by the final adjudication of
such issue.

Item 16. Exhibits.


Exhibit
Number                          Description
- ------                          -----------
       1(a)    --Declaration of Trust of BlackRock Multi-State Municipal Series
                 Trust (the "Trust"), dated August 2, 1985.(a)

        (b)    --Amendment to Declaration of Trust, dated September 18, 1987.(b)

        (c)    --Amendment to Declaration of Trust, dated December 21, 1987.(b)

        (d)    --Amendment to Declaration of Trust, dated October 3, 1988.(a)

        (e)    --Amendment to Declaration of Trust, dated February 27, 2002.(e)

        (f)    --Instrument establishing BlackRock New Jersey Municipal Bond
                 Fund (the "Fund") as a series of -- the Trust.(a)

        (g)    --Instrument establishing Class A and Class B shares of
                 beneficial interest of the Fund.(a)

        (h)    --Certificate of Establishment and Designation of Classes, dated
                 March 18, 2003.(l)

        (i)    --Form of Establishment and Designation of Classes.(o)

        (j)    --Form of Certification of Amendment to Declaration of Trust.(o)

       2       --Amended and Restated By-Laws of the Trust.(p)

       3       --Portions of the Declaration of Trust, Certificate of
                 Establishment and Designation and Amended and Restated
                 By-Laws of the Trust defining the rights of holders of the
                 Fund as a series of the Trust.(c)

       4       --Form of Agreement and Plan of Reorganization by and between
                 the Trust, on behalf of the Fund, and Lebenthal Funds, Inc.,
                 on behalf of Lebenthal New Jersey Municipal Bond Fund
                 ("Lebenthal New Jersey"), a series of Lebenthal Funds, Inc.(u)

       5(a)    --Form of Investment Advisory Agreement between the Trust, on
                 behalf of the Fund, and BlackRock Advisors, LLC (the
                 "Manager"). (u)

        (b)    --Form of Sub-Investment Advisory Agreement between the Manager
                 and BlackRock Investment Management, LLC. (u)

       6(a)    --Form of Unified Distribution Agreement between the Trust, on
                 behalf of the Fund, and FAM Distributors, Inc.(t)

        (b)    --Form of Unified Distribution Agreement between the Trust, on
                 behalf of the Fund, and BlackRock Distributors, Inc.(r)



                                     C-2


       7       --None.

       8       --Form of Custody Agreement between the Trust and State Street
                 Bank and Trust Company.(d)

       9(a)    --Form of Unified Transfer Agency, Dividend Disbursing Agency
                 and Shareholder Servicing Agency Agreement between the Trust
                 and PFPC, Inc.(t)

      (b)(1)   --Amended and Restated Credit Agreement between the Trust, on
                 behalf of the Fund, and a syndicate of banks.(f)

      (b)(2)   --Form of Second Amended and Restated Credit Agreement between
                 the Trust, on behalf of the Fund, a syndicate of banks and
                 certain other parties.(j)

      (b)(3)   --Form of Third Amended and Restated Credit Agreement between
                 the Trust, on behalf of the Fund, a syndicate of banks and
                 certain other parties.(k)

      (b)(4)   --Form of Fourth Amended and Restated Credit Agreement between
                 the Trust, on behalf of the Fund, a syndicate of banks and
                 certain other parties.(i)

      (b)(5)   --Form of Fifth Amended and Restated Credit Agreement between
                 the Trust, on behalf of the Fund, a syndicate of banks and
                 certain other parties.(n)

      (b)(6)   --Form of Sixth Amended and Restated Credit Agreement between
                 the Trust, on behalf of the Fund, a syndicate of banks and
                 certain other parties.(q)

      (c)      --Form of Administrative Services Agreement between the Fund
                 and State Street Bank and Trust Company.(g)

      10(a)    --Form of Unified Investor A Distribution Plan.(t)

        (b)    --Form of Unified Investor A1 Distribution Plan.(t)

        (c)    --Form of Unified Investor B Distribution Plan.(t)

        (d)    --Form of Unified Investor C Distribution Plan.(t)

        (e)    --Form of Unified Investor C1 Distribution Plan.(t)

        (f)    --Form of Unified Service Shares Distribution Plan.(s)

        (g)    --Select Pricing System Plan pursuant to Rule 18f-3.(r)

      11       --Opinion of Bingham McCutchen LLP, Massachusetts counsel.(u)

      12       --Tax opinion of Sidley Austin LLP, counsel for the Trust and
                 the Fund and special tax counsel for Lebenthal New Jersey.

      13(a)    --Consent of Deloitte & Touche LLP, independent registered
                 public accounting firm for the Registrant.(v)

        (b)    --Consent of Deloitte & Touche LLP, independent registered
                 public accounting firm for Lebenthal New Jersey for the fiscal
                 year ended November 30, 2005.(v)

        (c)    --Consent of PriceWaterhouseCoopers LLP, independent registered
                 public accounting firm for Lebenthal New Jersey for the fiscal
                 years ended prior to 2005.(v)



                                     C-3


      14       --None.

      15       --Code of Ethics.(m)

      16       --Power of Attorney.(v)

      17(a)    --Prospectus and Statement of Additional Information of the
                 Fund, each dated November 28, 2005.(h)

        (b)    --Prospectus and Statement of Additional Information of
                 Lebenthal Funds, each dated March 29, 2005.(h)

        (c)    --Annual Report to Shareholders of the Fund for the year ended
                 July 31, 2005.(h)

        (d)    --Annual Report to Shareholders of Lebenthal New Jersey for the
                 year ended November 30, 2005.(u)

        (e)    --Annual Report to Shareholders of Lebenthal New Jersey for the
                 year ended November 30, 2004.(u)

        (f)    --Form of Proxy.(u) [GRAPHIC OMITTED]


- --------------
 (a)  Filed on October 27, 1995 as an Exhibit to Post-Effective Amendment No.
      6 to the Fund's Registration Statement on Form N-1A (File No. 33-35441)
      (the "Registration Statement") under the Securities Act of 1933, as
      amended, (the "Securities Act").

 (b)  Incorporated by reference to Exhibits 1(b) and 1(c) to Post-Effective
      Amendment No. 13 to the Registration Statement on Form N-1A of Merrill
      Lynch New York Municipal Bond Fund, a series of the Trust (File No
      2-99473), filed on January 25, 1996.

 (c)  Reference is made to Article II, Section 2.3 and Articles V, VI, VIII,
      IX, X and XI of the Trust's Declaration of Trust, as amended, to the
      Certificates of Establishment and Designation establishing the Fund as a
      series of the Trust and establishing Class A and Class B shares of
      beneficial interest of the Fund, filed as Exhibit 1 to the Registration
      Statement; and to Articles I, V and VI of the Trust's Amended and
      Restated By-Laws, filed as Exhibit 2 to the Registration Statement.

 (d)  Incorporated by reference to Exhibit 7 to Post-Effective Amendment No.
      10 to the Registration Statement on Form N-1A of Merrill Lynch Maryland
      Municipal Bond Fund, a series of the Trust (File No. 33-49873), filed on
      October 30, 2001.

 (e)  Incorporated by reference to Exhibit 1(f) to Post-Effective Amendment
      No. 13 to the Registration Statement on Form N-1A of Merrill Lynch
      Florida Municipal Bond Fund, a series of the Trust (File No. 333-39555),
      filed on November 15, 2002.

 (f)  Incorporated by reference to Exhibit (b) to the Issuer Tender Offer
      Statement on Schedule TO of Merrill Lynch Senior Floating Rate Fund,
      Inc. (File No. 333-15973), filed on December 14, 2000.

 (g)  Incorporated by reference to Exhibit 8(d) to Post-Effective Amendment
      No. 1 to the Registration Statement on Form N-1A of Merrill Lynch Focus
      Twenty Fund, Inc. (File No. 333-89775), filed on March 20, 2001.

 (h)  Previously filed as Exhibits 17(a), 17(b) and 17(c), respectively, to
      the Registration Statement on Form N-14 of Merrill Lynch New Jersey
      Municipal Bond Fund of Merrill Lynch Multi-State Municipal Series Trust
      (File No. 333-130530) filed on December 20, 2005 (the "N-14 Registration
      Statement").

 (i)  Incorporated by reference to Exhibit 8(c)(4) to Post-Effective Amendment
      No. 8 to the Registration Statement on Form N-1A of Merrill Lynch Global
      Growth Fund, Inc. (File No. 333-32899), filed on December 4, 2003.

 (j)  Incorporated by reference to Exhibit (b)(2) to the Issuer Tender Offer
      Statement on Schedule TO of Merrill Lynch Senior Floating Rate Fund,
      Inc. (File No. 333-39837), filed on December 14, 2001.

 (k)  Incorporated by reference to Exhibit (b)(3) to the Issuer Tender Offer
      Statement on Schedule TO of Merrill Lynch Senior Floating Rate Fund,
      Inc. (File No. 333-39837), filed on December 13, 2002.

 (l)  Incorporated by reference to Exhibit 1(i) to Post-Effective Amendment
      No. 14 to the Registration Statement on Form N-1A of Merrill Lynch
      Florida Municipal Bond Fund, a series of the Trust (File No. 33-39555),
      filed on November 19, 2003.

 (m)  Incorporated by reference to Exhibit 15 to Pre-Effective Amendment No. 1
      to the Registration Statement on Form N-1A of Merrill Lynch Inflation
      Protected Fund (File No. 333-110936), filed on January 22, 2004.

 (n)  Incorporated by reference to Exhibit 8(c)(5) to Post-Effective Amendment
      No. 35 to the Registration Statement on Form N-1A of Merrill Lynch Bond
      Fund, Inc. (File No. 2-62329), filed on January 14, 2005.

 (o)  Filed on October 2, 2006 as an Exhibit to Post-Effective Amendment No.
      39 to the Registration Statement.

 (p)  Incorporated by reference to Exhibit 2 to Post-Effective Amendment No.
      16 to the Registration Statement on Form N-1A of Merrill Lynch Florida
      Municipal Bond Fund, a series of the Trust (File No. 33-39555), filed on
      November 25, 2005.

 (q)  Incorporated by reference to Exhibit 8(b)(6) to Post-Effective Amendment
      No. 24 to the Registration Statement on Form N-1A of Merrill Lynch U.S.
      Government Fund (File No. 2-92366), filed on December 21, 2005.

 (r)  Incorporated by reference to the identically numbered Exhibit to
      Post-Effective Amendment No. 38 to the Registration Statement on Form
      N-1A of Merrill Lynch Bond Fund, Inc. (File No. 2-62329), filed on July
      21, 2006.



                                     C-4


 (s)  Incorporated by reference to Exhibit 13(e) to Post-Effective Amendment
      No. 10 to the Registration Statement on Form N-1A of Merrill Lynch Large
      Cap Series Funds, Inc. (File No. 333-89389), filed on September 22,
      2006.

 (t)  Incorporated by reference to an Exhibit to Post-Effective Amendment No.
      39 to the Registration Statement on Form N-1A of Merrill Lynch Bond
      Fund, Inc. (File No. 2-62329), filed on September 15, 2006.

 (u)  Previously filed as an Exhibit to the N-14 Registration Statement filed
      on February 1, 2006.

 (v)  Previously filed as an Exhibit to the N-14 Registration Statement filed
      on February 3, 2006.


- -------------

Item 17. Undertakings.

      (1) The undersigned Registrant agrees that prior to any public
reoffering of the securities registered through use of a prospectus which is
part of this Registration Statement by any person or party who is deemed to be
an underwriter within the meaning of Rule 145(c) of the Securities Act of
1933, as amended, the reoffering prospectus will contain information called
for by the applicable registration form for reofferings by persons who may be
deemed underwriters, in addition to the information called for by other items
of the applicable form.

      (2) The undersigned Registrant agrees that every prospectus that is
filed under paragraph (1) above will be filed as part of an amendment to the
registration statement and will not be used until the amendment is effective,
and that, in determining any liability under the Securities Act of 1933, as
amended, each post-effective amendment shall be deemed to be a new
registration statement for the securities offered therein, and the offering of
securities at that time shall be deemed to be the initial bona fide offering
of them.

      (3) The Registrant undertakes to file, by post-effective amendment, an
opinion of counsel as to certain tax matters, within a reasonable time after
receipt of such opinion.



                                     C-5


                                  SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the
Registrant has duly caused this Amendment to its Registration Statement to be
signed on its behalf by the undersigned, thereunto duly authorized, in the
Township of Plainsboro, and State of New Jersey, on the 23rd day of October,
2006.

                              BLACKROCK MULTI -STATE MUNICIPAL SERIES TRUST
                              (Registrant)

                              BY: /S/ DONALD C. BURKE

                              -----------------------------------------------
                              (Donald C. Burke, Vice President and Treasurer)

      As required by the Securities Act of 1933, this Registration Statement
has been signed by the following persons in the capacities and on the dates
indicated.



          Signature                                  Title                                       Date
          ---------                                  -----                                       ----
                                                                             
    ROBERT C. DOLL, JR.*          President (Principal Executive Officer) and
- -----------------------------                       Trustee
    (Robert C. Doll, Jr.)

      DONALD C. BURKE*              Vice President and Treasurer (Principal
- -----------------------------          Financial and Accounting Officer)
      (Donald C. Burke)

     JAMES H. BODURTHA*                             Trustee
- -----------------------------
     (James H. Bodurtha)

      KENNETH A. FROOT*                             Trustee
- -----------------------------
     (Kenneth A. Froot)

         JOE GRILLS*                                Trustee
- -----------------------------
        (Joe Grills)

     HERBERT I. LONDON*                             Trustee
- -----------------------------
     (Herbert I. London)

    ROBERTA COOPER RAMO*                            Trustee
- -----------------------------
    (Roberta Cooper Ramo)

   ROBERT S. SALOMON, JR.*                          Trustee
- -----------------------------
  (Robert S. Salomon, Jr.)


*By:           /s/ Donald C. Burke                                                 October 23, 2006
     ----------------------------------------
       (Donald C. Burke, Attorney-In-Fact)




                                     C-6


                                 EXHIBIT INDEX
Exhibit
Number   Description
- ------   -----------

    12   -- Tax opinion of Sidley Austin LLP, counsel for the Trust and the
            Fund and special tax counsel for Lebenthal New Jersey.



                                     C-7