The ten teams competed in a double round-robin tournament, one game at home and one away.
The First Stage winner and runner-up qualified to the 2004 Copa Sudamericana.
At the end of the Second Stage, the two teams with the fewest points were relegated to the Serie B.
The Liguilla Final was a double round-robin tournament between the six qualified teams of the First and Second Stage.
The winner of the Liguilla Final was crowned the Serie A champion.