SECURITIESFORM AND EXCHANGE COMMISSION Washington, D.C. 20549 6-K

~~FORM~~UNITED ~~6-K~~ STATES

~~Report~~SECURITIES ofAND ~~Foreign~~EXCHANGE ~~Private Issuer~~ COMMISSION

~~Pursuant~~Washington, toD.C. ~~Rule 13a-16 or 15d-16 of the Securities Exchange Act of 1934~~ 20549

ForReport the month of August,Foreign 2004Private Issuer

Commission FilePursuant Number:to 001Rule 13a-1037816 or 15d-16 of the Securities Exchange Act of 1934

~~AVENTIS (Translation~~For the month of ~~registrant's~~October ~~name into English)~~ 2004

~~67917 Strasbourg CEDEX 9~~Commission ~~France (Address~~File ~~of principal executive offices)~~ Number: 001-10378

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

~~Form 20-F ý Form 40-F o~~(Translation of registrant’s name into English)

~~Indicate~~67917 byStrasbourg, ~~check~~cedex ~~mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): o~~ 9

~~Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): o~~ France

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

~~Yes o No~~ Indicate by check mark whether the registrant files or will file annual ý reports under cover Form 20-F or Form 40-F.

IfForm ~~"Yes" is marked, indicate below the file number assigned to the registrant in connection with Rule~~20-F ~~12g3~~ ý Form 40-~~2(b):~~F ~~Not applicable~~ o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as ~~EXHIBIT~~permitted ~~LIST~~ by Regulation S-T Rule 101(b)(1): o

Exhibit		Description
99.1		Press release, dated August 31, 2004, relating to the new composition of Aventis Supervisory Board and Management Board.
99.2		Press release, dated August 31, 2004, relating to approval of dividend at Annual General Meeting of Hoechst AG.

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): o

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

~~Pursuant~~Yes too No ~~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.~~ ý

			AVENTIS(Registrant)
Date: August 31, 2004		By:	/s/ DIRK OLDENBURG Name: Dirk Oldenburg Title: General Legal Counsel

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): Not applicable

~~QuickLinks~~On October 4, 2004, Aventis issued the press release attached hereto as Exhibit 99.1.

Exhibit 99.1 is incorporated herein by reference.

Exhibit List

Exhibit No.		Description
Exhibit 99.1		Press Release dated October 4, 2004, relating to Apidra^®.

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.

			AVENTIS
			(Registrant)

Date: October 4, 2004	By:	/s/ Dirk Oldenburg

		Name: Dirk Oldenburg
		Title: General Legal Counsel

Exhibit Index

Exhibit No.		Description
Exhibit 99.1		Press Release dated October 4, 2004, relating to Apidra^®.

Filing Compare · AVENTIS