The 2003–04 season was Sport Lisboa e Benfica's 100th season in existence and the club's 70th consecutive season in the top flight of Portuguese football. It ran from 1 July 2003 to 30 June 2004. Benfica competed domestically in the Primeira Liga and the Taça de Portugal. The club also participated in the UEFA Champions League as a result of finishing second in the Primeira Liga in the previous season.