The 2004 Indian general election polls in Tamil Nadu were held for 39 seats in the state. The result was a victory for the Democratic Progressive Alliance, which included the United Progressive Alliance (UPA) and its allies the Left Front which won all 39 seats in the state. DMK and its allies were also able to hold on to Pondicherry, which has 1 seat, which allowed the UPA to win all 40 seats in Tamil Nadu and Pondicherry. The 2 larger partners Dravida Munnetra Kazhagam (DMK) (16) and Indian National Congress (INC) (10) won the majority of seats, with the junior partners Pattali Makkal Katchi (PMK) (5) and Marumaralarchi Dravida Munnetra Kazhagam (MDMK) (4) winning the rest. The remaining 4 seats were won by the Left Front parties. Due to the support of the Left Front for the government at the centre, all 39 seats in Tamil Nadu, supported the formation of the UPA-led government.

General elections were held in India in four phases between 20 April and 10 May 2004. Over 670 million people were eligible to vote, electing 543 members of the 14th Lok Sabha. Seven states also held assembly elections to elect state governments. They were the first elections fully carried out with electronic voting machines.