The 2004 GP Ouest-France was the 68th edition of the GP Ouest-France cycle race and was held on 29 August 2004. The race started and finished in Plouay. The race was won by Didier Rous of the Brioches La Boulangère team.

Final general classification[2][3] Rank Rider Team Time 1  Didier Rous (FRA) Brioches La Boulangère 4h 31' 27" 2  Serge Baguet (BEL) Lotto–Domo + 0" 3  Guido Trentin (ITA) Cofidis + 2" 4  Danilo Hondo (GER) Gerolsteiner + 2" 5  Giulio Tomi (ITA) Vini Caldirola–Nobili Rubinetterie + 2" 6  Vladimir Duma (UKR) Landbouwkrediet–Colnago + 2" 7  Patrick Calcagni (SUI) Vini Caldirola–Nobili Rubinetterie + 2" 8  Cédric Vasseur (FRA) Cofidis + 2" 9  Sergio Barbero (ITA) Lampre + 2" 10  Fabian Wegmann (GER) Gerolsteiner + 2"