2004–05 Primera División A season

Primera División A (Méxican First A Division) is a Mexican football tournament. This season was composed of Apertura 2004 and Clausura 2005. San Luis was the winner of the promotion to First Division after winning Querétaro in the promotion playoff.

Changes for the 2004–05 season

 * Leones de Morelos was acquired by new owners, for that reason the team was moved to Querétaro and was renamed to Querétaro F.C.
 * Azucareros de Córdoba was relocated in Colima and renamed Huracanes de Colima.
 * Guerreros de Tlaxcala was relocated to Ciudad Obregón and renamed Pioneros de Obregón.
 * C.D. Guadalajara moved its reserve team, Tapatío, to La Piedad and renamed to Chivas La Piedad.
 * Atlante F.C. moved its reserve team, Guerreros de Acapulco, to Ciudad Nezahualcóyotl and renamed Potros Neza.
 * Tigrillos moved from Mexico City to Los Mochis and became Tigrillos Broncos.
 * Pachuca Juniors and Lobos BUAP were promoted from Second Division.

Promotion final
The Promotion Final faced San Luis against Querétaro to determine the winner of the First Division Promotion. San Luis was the winner.

Relegation play-out
The Football Association determined the celebration of a promotion series between the penultimate team of the Primera 'A' Relegation Table against the runner-up of the Second Division, this series faced Chivas La Piedad against the Cachorros UdeG. Chivas La Piedad won the series and remained in the category.