The 2003 FIA Sportscar Championship was the third season of FIA Sportscar Championship, an auto racing series regulated by the Fédération Internationale de l'Automobile and organized by the International Racing Series Ltd. It was the seventh and final season of the series dating back to the International Sports Racing Series of 1997. The series featured sports prototypes divided into two categories, SR1 and SR2, and awarded championships for drivers, constructors, and teams in both classes. The series began on 13 April 2003 and ended on 21 September 2003 after seven races in Europe.
Jan Lammers of the Netherlands won his second consecutive drivers championship for his Racing for Holland Dome outfit, sharing the championship with countryman John Bosch. Mirko Savolid and Pierguiseppe Peroni also earned a repeat drivers championship in the SR2 category for Lucchini Engineering after winning in five of seven events.