The 2003 Campeonato Brasileiro Série A was the 47th edition of the Campeonato Brasileiro Série A. The first edition with only a double round-robin and no playoffs, it began on March 29, 2003, and reached its end on December 14. The competition was won by Cruzeiro Esporte Clube, who completed a treble.
The 24 teams played against each other twice. At the season finale, the team with the most accumulated points (3 for each win, 1 for a draw, none for a loss) was declared champion. The two lowest-placed teams were relegated to the Campeonato Brasileiro Série B of the following year.
^Ponte Preta docked the points conquisted in the matches against Internacional and Juventude for the irregulate fielding of the player Roberto. Otherwise, Internacional won 2 points and Juventude won 3 points.
^Paysandu docked 8 points due to irregularities fielding of the players Júnior Amorim and Aldrovani. In other way, three points won to Ponte Preta, three for São Caetano, two for Corinthians and two for Fluminense.