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.
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.