Luxembourg competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.

A total of 10 athletes, 6 men and 4 women, competed in 6 sports; most of them participated strongly in road cycling, swimming, and tennis.

Notable Luxembourgish athletes featured road cyclist Fränk Schleck, triathlete Elizabeth May, and tennis star Claudine Schaul, who later became the nation's flag bearer in the opening ceremony.

Benoît Joachim was the only entrant in the time trial, but finished well back.

Luxembourgish swimmers earned qualifying standards in the following events (up to a maximum of 2 swimmers in each event at the A-standard time, and 1 at the B-standard time): Anne Kremer and Claudine Schaul both lost their single matches in straight sets to higher ranking opponents, then paired up as a double team, and lost an upset to a wildcard entry from Colombia in three sets, including a tiebreak set and a 16-game final set.