The 1990–91 Primera División de Fútbol Profesional season is the 39th tournament of El Salvador's Primera División since its establishment of the National League system in 1948. The tournament began August 12, 1990 and ended on June 30, 1991. Luis Angel Firpo won the championship match against Aguila 1-0.
Luis Angel Firpo went 31 games undefeated, the second longest undefeated run at the time. Since that time, Alianza and FAS 33 games in 1977-78 games.
Prior to the start of 1990-91 season, Acajutla changed their names to Tiburones FC (the sharks). They also changed their team colour from red to white and orange.