The men's decathlon event at the 2004 World Junior Championships in Athletics was held in Grosseto, Italy, at Stadio Olimpico Carlo Zecchini on 14 and 15 July. Junior implements (valid until 2005) were used, i.e. 106.7 cm (3'6) (senior implement) hurdles, as well as 6 kg shot and 1.75 kg discus.