The Ninth Seimas of Lithuania was a parliament (Seimas) elected in Lithuania. Elections took place on 10 October 2004, with the run-off on 24 October. The Seimas commenced its work on 15 November 2004 and served a four-year term, with the last session on 16 November 2008.

The Seimas of the Republic of Lithuania, or simply the Seimas, is the unicameral legislative body of the Republic of Lithuania. The Seimas constitutes the legislative branch of government in Lithuania, enacting laws and amendments to the Constitution, passing the budget, confirming the Prime Minister and the Government and controlling their activities.