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) May 16, 2005

MS Structured Asset Corp. (Issuer in Respect of SATURNS Trust No. 2004-3)
(Exact name of registrant as specified in its charter)

Delaware
(State or other jurisdiction
of incorporation)

001-32009
(Commission
File Number)

13-4026700
(IRS Employer
Identification No.)

1585 Broadway, New York, New York
(Address of principal executive offices)

10036
(Zip Code)

Registrant's telephone number, including area code 212-761-2520

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

[ ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

[ ] Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

[ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

[ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Section 8 - Other Events

Item 8.01. Other Events.

This current report on Form 8-K relates to the semi annual distribution reported to the holders of SATURNS Trust No. 2004-3, which was made on May 16, 2005.

Section 9 - Financial Statements and Exhibits

Item 9.01 Financial Statements and Exhibits.

99.1 Semi-Annual Distribution report pursuant to the Trust Agreement for the distribution on May 16, 2005.

(Exhibit No. Description)

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.

LASALLE BANK NATIONAL ASSOCIATION, IN ITS CAPACITY AS TRUSTEE UNDER THE TRUST AGREEMENT ON BEHALF OF MS STRUCTURED ASSET CORP. REGISTRANT

By: /s/ Russell Goldenberg
Russell Goldenberg
Group Senior Vice President

Date: May 19, 2005

Structured Asset Trust Unit Repackagings (SATURNS)

AT&T Corp. Debenture Backed

Series 2004-3

ABN AMRO Acct: 721701.1

Reporting Package Table of Contents

Payment Date:
Prior Payment:
Next Payment:
Record Date:

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

Administrator:
Andy Streepey 312.904.9387
andy.streepey@abnamro.com

Analyst:
Anty Huang 714.259.6269
anty.huang@abnamro.com

Statement Date:

135 S. LaSalle Street, Suite 1625
Chicago, IL 60603
USA

Statements to Certificateholders
Cash Reconciliation Summary
Bond Interest Reconciliation
Other Related Information

Other Related Information

Rating Information
Realized Loss Detail

Page 2
Page 3
Page 4
Page 5

Page 6

Page 7
Page 8

Page(s)

Information is available for this issue from the following sources

Issue Id:

Monthly Data File
Name:

SAT00403

SAT00403_200505_3.ZIP

Closing Date:

First Payment Date:

Rated Final Payment: Date:

26-Feb-04
17-May-04

15-Nov-31

Parties to The Transaction

Depositor: MS Structured Asset Corp

Underwriter: Morgan Stanley & Co. Incorporated

Rating Agency: Moody's Investors Service, Inc./Standard & Poor's

800.246.5761

LaSalle Factor Line

LaSalle Web Site

www.etrustee.net

Page 1 of 8

Class

CUSIP

Original

Opening

Principal

Negative

Closing

Interest

Pass-Through

Per $ 1000

Next Rate(3)

WAC:
WAMM:

Payment Date:
Prior Payment:
Next Payment:
Record Date:

9.725576%

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

Structured Asset Trust Unit Repackagings (SATURNS)

AT&T Corp. Debenture Backed

Series 2004-3

Face Value (1)

Balance

Payment

Adj. or Loss

Amortization

Balance

Payment (2)

Adjustment

Rate

394

Grantor Trust

Statement Date:

ABN AMRO Acct: 721701.1

1000.000000000

0.000000000

1000.000000000

37.750000000

Fixed

0.00

0.000000000

7.55000000%

0.000000000

80411L207

A UNIT

45,000,000.00

0.00

45,000,000.00

1,698,750.00

45,000,000.00

1000.000000000

0.000000000

1000.000000000

45.270000000

0.00

0.000000000

0.00000000%

0.000000000

80411LAA6

B UNIT

10,813,000.00

0.00

10,813,000.00

489,504.51

10,813,000.00

Total P&I Payment

0.00

45,000,000.00

2,188,254.51

Total

45,000,000.00

0.00

2,188,254.51

Page 2 of 8

Notes: (1) N denotes notional balance not included in total (2) Accrued Interest Plus/Minus Interest Adjustment Minus Deferred Interest equals Interest Payment (3) Estimated. * Denotes Controlling Class

Structured Asset Trust Unit Repackagings (SATURNS)

Payment Date:
Prior Payment:
Next Payment:
Record Date:

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

AT&T Corp. Debenture Backed

Series 2004-3

ABN AMRO Acct: 721701.1

Statement Date:

Cash Reconciliation Summary

Current Scheduled Interest

Interest Summary

Less Deferred Interest

Plus Gross Advance Interest

Less PPIS Reducing Scheduled Int

2,188,254.51

0.00
0.00

Less ASER Interest Adv Reduction

0.00

Less Other Adjustment

0.00

Total

2,188,254.51

Unscheduled Interest:
Prepayment Penalties

0.00

Yield Maintenance Penalties

0.00

Other Interest Proceeds

0.00

Total

0.00

Less Fees & Expenses Paid By/To Servicer

Less Fee Paid To Servicer
Less Fee Strips Paid by Servicer

Special Servicing Fees

Interest Due Serv on Advances

Recoup of Prior Advances

Misc. Fees & Expenses

Total Unscheduled Fees & Expenses
Total Interest Due Trust

Less Fees & Expenses Paid By/To Trust
Trustee Fee
Fee Strips
Misc. Fees
Interest Reserve Withholding

Plus Interest Reserve Deposit
Total

Total Interest Due Certs

Principal Summary

Scheduled Principal:
Current Scheduled Principal
Advanced Scheduled Principal
Scheduled Principal
Unscheduled Principal:
Curtailments
Prepayments in Full
Liquidation Proceeds
Repurchase Proceeds
Other Principal Proceeds
Total Unscheduled Principal
Remittance Principal

Remittance P&I Due Trust

Remittance P&I Due Certs

Pool Balance Summary

Beginning Pool
Scheduled Principal
Unscheduled Principal
Deferred Interest
Liquidations
Repurchases

Ending Pool

Balance

Count

Principal

Interest

Prior Outstanding
Plus Current Period
Less Recovered

Ending Outstanding

Servicing Fee Summary

Current Servicing Fees
Plus Fees Advanced for PPIS
Less Reduction for PPIS
Plus Delinquent Servicing Fees

Total Servicing Fees

PPIS Summary

Gross PPIS
Reduced by PPIE
Reduced by Shortfalls in Fees
Reduced by Other Amounts

PPIS Reducing Scheduled
Interest

PPIS Reducing Servicing Fee
PPIS Due Certificate

0.00

0.00
0.00

0.00

2,188,254.51

0.00
0.00
0.00
0.00

0.00

0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00
0.00

2,188,254.51

45,000,000.00

0.00
0.00

0.00

45,000,000.00

0.00

0.00
0.00
0.00
0.00

0.00

0.00
0.00
0.00
0.00
0.00
0.00

0.00

2,188,254.51

Interest Not Advanced (

Current Period

)

0.00

Workout Fees
Liquidation Fees

0.00
0.00

Less Non Recovered

0.00

0.00
0.00

0.00

Advance Summary (Advance Made by Servicer)

Page 3 of 8

Structured Asset Trust Unit Repackagings (SATURNS)

Class

Accrued

Payment Date:
Prior Payment:
Next Payment:
Record Date:

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

AT&T Corp. Debenture Backed

Series 2004-3

ABN AMRO Acct: 721701.1

Bond Interest Reconciliation

Deductions

Allocable

Deferred &

Prior

Prepay-

Other

Additions

Interest

Credit Support

Original

Current(4)

Accrual

Int. Short-

falls Due

ment

Interest

Interest (2)

Payment

Amount

PPIS

Interest

Certificate

Accretion

Interest

Loss/Exp

Interest

Penalties

Proceeds (1)

Interest

Shortfalls

Certificate

Rate

Pass

Thru

Method Days

Outstanding

Remaining

Statement Date:

Distributable

Current Period

(Shortfall)/

Recovery

Int Accrual

on Prior

Shortfall (3)

0.00

A UNIT

180

1,698,750.00

0.00

30/360

7.550000000%

0.00

B UNIT

180

489,504.51

0.00

30/360

0.000000000%

0.00

2,188,254.51

0.00

(2) Accrued - Deductions + Additions Interest

(3) Includes interest accrued on outstanding Interest Shortfalls and/or Loss Allocations. Where applicable.

Page 4 of 8

(1) Other Interest Proceeds are additional interest amounts specifically allocated to the bond(s) and used in determining the bonds Distributable Interest.

(4) Determined as follows: (A) the ending balance of all the classes less (B) the sum of (i) the ending balance of the class and (ii) the ending balance of all classes which are not subordinate to the class divided by (A).

Structured Asset Trust Unit Repackagings (SATURNS)

Payment Date:
Prior Payment:
Next Payment:
Record Date:

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

AT&T Corp. Debenture Backed

Series 2004-3

ABN AMRO Acct: 721701.1

Other Related Information

Statement Date:

Swap Receipents

Swap Amount Received

Next Swap Rate

None

0.00

0.00%

Swap Information

Page 5 of 8

Structured Asset Trust Unit Repackagings (SATURNS)

Payment Date:
Prior Payment:
Next Payment:
Record Date:

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

AT&T Corp. Debenture Backed

Series 2004-3

ABN AMRO Acct: 721701.1

Other Related Information

Statement Date:

The underlying security issuer or guarantor, as applicable, is subject to the informational requirements of the Exchange Act. The
underlying security issuer or guarantor, as applicable, currently files reports, proxy statements and other information with the SEC.
Those periodic reports, current reports and other reports and other information can be inspected and copied at the public reference
facilities maintained by the SEC at Room 1024, 450 Fifth Street, N.W., Washington, D.C. 20549, at prescribed rates. The SEC also
maintains a website on the internet at http://www.sec.gov at which users can view and download copies of reports, proxy, information
statements and other information filed electronically. In addition, those reports and other information may also be obtained from the
underlying security issuer by making a request to the underlying security issuer.

Effective for the 5/16/05 payment, the interest rate payable on the Class A Units is increased to 7.550%. Pursuant to the
SATURNS 2004-3 trust agreement, the interest rate payable on the Class A Units is increased by 0.20% for each rating notch
downgrade of the underlying securities. Both Moody's and S&P have downgraded the underlying securities two notches (four total
rating notch downgrades). Therefore, the interest payable to the Class A Units is increased by 0.80%."

"Effective for the 5/16/05 payment, the amount payable on the Class B Units is increased to $4.16 per Unit. Pursuant to the
SATURNS 2004-3 trust agreement, the amount payable on the Class B Units is increased by $1.04 for each rating notch downgrade
of the underlying securities. Both Moody's and S&P have downgraded the underlying securities two notches (four total rating notch
downgrades). Therefore, the amount payable to the Class B Units is increased by $4.16 per Unit.

Page 6 of 8

Structured Asset Trust Unit Repackagings (SATURNS)

Payment Date:
Prior Payment:
Next Payment:
Record Date:

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

AT&T Corp. Debenture Backed

Series 2004-3

ABN AMRO Acct: 721701.1

Rating Information

Class

CUSIP

Fitch

Moody's

S&P

Fitch

Moody's

S&P

Original Ratings

Rating Change/Change Date(1)

Statement Date:

A UNIT

80411L207

Baa2

BBB

Ba1

3/11/05

BB+

2/16/05

B UNIT

80411LAA6

Baa2

BBB

Ba1

3/11/05

BB+

2/16/05

Page 7 of 8

NR - Designates that the class was not rated by the rating agency.

(1) Changed ratings provided on this report are based on information provided by the applicable rating agency via electronic transmission. It shall be understood that this transmission will generally have been provided to
LaSalle within 30 days of the payment date listed on this statement. Because ratings may have changed during the 30 day window, or may not be being provided by the rating agency in an electronic format and therefore
not being updated on this report, LaSalle recommends that investors obtain current rating information directly from the rating agency.

Structured Asset Trust Unit Repackagings (SATURNS)

Payment Date:
Prior Payment:
Next Payment:
Record Date:

16-May-05
16-May-05

15-Nov-04
15-Nov-05

11-May-05

AT&T Corp. Debenture Backed

Series 2004-3

ABN AMRO Acct: 721701.1

Realized Loss Detail

Period

Disclosure

Control #

Appraisal

Date

Appraisal

Value

Beginning
Scheduled

Balance

Gross

Proceeds

Gross Proceeds

as a % of

Sched. Balance

Aggregate

Liquidation

Expenses *

Net

Liquidation

Proceeds

Net Proceeds

as a % of

Sched. Balance

Realized

Loss

Statement Date:

Current Total
Cumulative

Page 8 of 8

* Aggregate liquidation expenses also include outstanding P&I advances and unpaid servicing fees, unpaid trustee fees, etc..

MS STRUCTURED SATURNS SERIES 2004-3 8-K