UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported)

25-May-04

Credit Suisse First Boston Mortgage Securities Corp. Home Equity Asset Trust 2004-1, Home Equity Pass-Through Certificates, Series 2004-1

Credit Suisse First Boston Mortgage Securities Corp.

(Exact Name of Registrant as Specified in its Charter)

Delaware

333-107055-22

13-3320910

(State or Other Jurisdiction

Of Incorporation)

(Commission

File Number)

(I.R.S. Employer

Identification No.)

11 Madison Avenue

New York, New York

(Address of Principal
Executive Offices)

10010

(Zip Code)

Registrant's telephone number, including area code: (212) 325-2000

Item 5. Other Events

On 25-May-04 a scheduled distribution was made from the Trust to holders of the Certificates. The Trustee has caused to be filed with the Commission, the Monthly Report dated 25-May-04. The Monthly Report is filed pursuant to and in accordance with (1) numerous no-action letters (2) current Commission policy in the area.

Item 7. Monthly Statements and Exhibits

The following is filed herewith. The exhibit number corresponds with Item 601(b) of Regulation S-K.

Exhibit No. 99.1

Monthly Distribution Report dated: 25-May-04

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

By: U.S. Bank National Association, as Trustee for:

Credit Suisse First Boston Mortgage Securities Corp. Home Equity Asset Trust 2004-1

Home Equity Pass-Through Certificates

SERIES 2004-1

By:

/s/ Sheryl Christopherson

Name:

Sheryl Christopherson

Title:

Vice President

Dated: 25-May-04

Index to Exhibits

Exhibit No. 99.1

Monthly Distribution Report dated: 25-May-04

CFSB MOR SEC CORP HOME EQUITY ASSET TRUST 2004-1 8-K