SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

Report of Foreign Issuer

Pursuant to Rule 13a-16 or 15d-16 of ~~the Securities Exchange Act of 1934~~

~~For~~ the Securities ~~month~~Exchange Act of ~~February, 2005~~ 1934

For the month of April, 2005

CIBA SPECIALTY CHEMICALS HOLDING INC.

(Exact name of Registrant as specified in its charter)

Klybeckstrasse ~~141~~ ~~4002 Basel Switzerland~~ 141

4002 Basel

Switzerland

(Address of principal executive offices)

(Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.)

Form 20-F þx Form 40-F o

(Indicate by check mark whether the registrant by furnishing the information contained in this ~~Form,~~form ~~the Registrant~~ is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2 (b) under the Securities Exchange Act of 1934.)

Yes o No þx

(If “"Yes” " is marked, indicate below the file number assigned to the registrant in ~~connection~~ connection with Rule 12g3-2 (b))

CIBA SPECIALTY CHEMICALS HOLDING INC.

On ~~February 1~~April 21, 2005, Ciba Specialty Chemicals Holding Inc., a stock corporation, ~~organized~~issued ~~under the~~a ~~laws~~News ofRelease ~~Switzerland,~~regarding ~~issued~~its athree ~~news~~month ~~release~~(or ~~addressing~~first ~~its~~quarter) ~~financial~~ results ~~of 2004~~2005. A copy of ~~the Annual~~this ~~Report 2004 and~~ News Release ~~are~~is ~~hereby furnished pursuant to Rule 13a-16 of the Securities Exchange Act of 1934 and~~ attached hereto as Exhibit 99.1 and ~~99.2, respectively and~~ incorporated by by reference herein.

2EXHIBIT INDEX

EXHIBIT LIST

Exhibit	Description
99.1	News Release: Three Month Results 2005, dated April 21, 2005

Exhibit		Description
99.1		Annual Report 2004
99.2		News Release dated February 1, 2005 of Ciba Specialty Chemicals Holding Inc.

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, thereunto duly authorized.

Ciba Specialty Chemicals Holding Inc. (Registrant) ~~By /s/ Oliver Strub Oliver Strub Senior Corporate Counsel~~

/s/ Max Dettwiler Max Dettwiler Head Taxes, Insurance & Corporate Law

Date April 21, 2005	By /s/ Oliver Strub	/s/ Max Dettwiler
	Oliver Strub	Max Dettwiler
	Head, Corporate Law	Head, Taxes, Corporate Law & Insurance

Date February 1, 2005

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