FILE NO. 333-
CIK #1531295

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549-1004

Registration Statement
on
Form S-6

For Registration under the Securities Act of 1933 of Securities of Unit
Investment Trusts Registered on Form N-8B-2.

A. Exact name of Trust: VAN KAMPEN UNIT TRUSTS, SERIES 1221

B. Name of Depositor: VAN KAMPEN FUNDS INC.

C. Complete address of Depositor's principal executive offices:

11 Greenway Plaza
Houston, Texas 77046-1173

D. Name and complete address of agents for service:

PAUL HASTINGS LLP VAN KAMPEN FUNDS INC.
Attention: Michael R. Rosella, Esq. Attention: John M. Zerr, Esq.
75 East 55th Street 11 Greenway Plaza
New York, New York 10022 Houston, Texas 77046-1173

E. Title of securities being registered: Units of fractional undivided beneficial interest

F. Approximate date of proposed sale to the public:

AS SOON AS PRACTICABLE AFTER THE EFFECTIVE DATE OF THE REGISTRATION STATEMENT

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 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a) may determine.

Preliminary Prospectus Dated March 15, 2012

VAN KAMPEN UNIT TRUSTS, SERIES 1221

Preferred Opportunity Portfolio, Series 18

The attached final Prospectus for a prior series of the fund is hereby used as a preliminary Prospectus for the above stated series. The narrative information and structure of the attached final Prospectus will be substantially the same as that of the final Prospectus for this series. Information with respect to pricing, the number of units, dates and summary information regarding the characteristics of securities to be deposited in this series is not now available and will be different since each series has a unique Portfolio. Accordingly, the information contained herein with regard to the previous series should be considered as being included for informational purposes only. Ratings of the securities in this series are expected to be comparable to those of the securities deposited in the previous series. However, the Estimated Current Return for this series will depend on the interest rates and offering prices of the securities in this series and may vary materially from that of the previous series.

Information contained herein is subject to completion or amendment. Such units may not be sold nor may an offer to buy be accepted prior to the time the registration statement becomes effective. This Prospectus shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of the units in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

(Incorporated herein by reference is the final prospectus from Van Kampen Unit Trusts, Series 1192 (Registration No. 333-178580) as filed on February 17, 2012, which shall be used as a preliminary prospectus for the current series of the fund.)

The Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this Prospectus. Any representation to the contrary is a criminal offense.

CONTENTS OF REGISTRATION STATEMENT

This Registration Statement comprises the following papers and documents:

The Facing Sheet of Form S-6.
The Prospectus.
The Signatures.
The Written Consents of Legal Counsel, Evaluator and Independent Registered Public Accounting Firm.

The following exhibits:

 1.1 Trust Agreement (to be supplied by amendment).

1.1.1 Standard Terms and Conditions of Trust. Reference is made to Exhibit
 1.1.1 to the Registration Statement on Form S-6 of Van Kampen Focus
 Portfolios, Series 284 (File No. 333-57836) dated May 2, 2001.

 1.2 Certificate of Incorporation of Van Kampen Funds Inc. Reference is
 made to Exhibit 1.2 to the Registration Statement on Form S-6 of Van
 Kampen Focus Portfolios, Series 320 (File No. 333-75548) dated January
 2, 2002.

 1.3 By-laws of Van Kampen Funds Inc. Reference is made to Exhibit 1.3 to
 the Registration Statement on Form S-6 of Van Kampen Focus Portfolios,
 Series 320 (File No. 333-75548) dated January 2, 2002.

 1.4 Form of Dealer Agreement. Reference is made to Exhibit 1.4 to the
 Registration Statement on Form S-6 of Van Kampen Unit Trusts,
 Municipal Series 560 (File No. 333-122799) dated May 18, 2005.

 2.1 Form of Code of Ethics. Reference is made to Exhibit 2.1 to the
 Registration Statement on Form S-6 of Van Kampen Unit Trusts,
 Municipal Series 890 (File No. 333-165240) dated June 2, 2010.

 3.1 Opinion and Consent of Counsel as to legality of securities being
 registered (to be supplied by amendment).

 3.3 Opinion of Counsel as to the Trustee and the Trust (to be supplied by
 amendment).

 4.1 Consent of Initial Evaluator (to be supplied by amendment).

 4.2 Consent of Independent Registered Public Accounting Firm (to be
 supplied by amendment).

 6.1 List of Officers and Directors of Van Kampen Funds Inc. Reference is
 made to Exhibit 6.1 to the Registration Statement on Form S-6 of Van
 Kampen Unit Trusts, Municipal Series 1019 (File No. 333-176336) dated
 October 12, 2011.

 7.1 Powers of Attorney. Reference is made to Exhibit 7.1 to the
 Registration Statement on Form S-6 of Van Kampen Unit Trusts,
 Municipal Series 890 (File No. 333-165240) dated June 2, 2010 and Van
 Kampen Unit Trusts, Taxable Income Series 332 (File No. 333-174177)
 dated July 14, 2011.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant, Van Kampen Unit Trusts, Series 1221, has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized in the City of Chicago and State of Illinois on the 15th day of March, 2012.

VAN KAMPEN UNIT TRUSTS, SERIES 1221
(Registrant)

By: VAN KAMPEN FUNDS INC.
(Depositor)

By: /s/ JOHN F. TIERNEY
 -------------------
 Vice President

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below on March 15, 2012, by the following persons who constitute the principal officers and a majority of the Board of Directors of Van Kampen Funds Inc.:

 SIGNATURE TITLE

John S. Cooper Director and President

Steven Massoni Director and President

Annette J. Lege Treasurer and Chief Financial Officer

 By: /s/ JOHN F. TIERNEY
 -------------------
 (Attorney-in-fact*)