Independiente Medellín were the defending champions, having won the 2002 Finalización tournament.
The Torneo Apertura (officially the 2003 Copa Mustang I for sponsorship reasons) was the first tournament of the season.
The Torneo Finalización (officially the 2003 Copa Mustang II for sponsorship reasons) was the second tournament of the season.
An aggregate table including all games that a team played during the year was used to determine berths to both the Copa Libertadores and the Copa Sudamericana.
The best-placed non-champion qualified for the 2004 Copa Libertadores along with both champions of the season, while the second and third best-placed non-champions qualified for the 2004 Copa Sudamericana.