This research work involves the improvement of the male line MLS4-1 of the hybrid AN-388 which was released by the Instituto Mexicano del Maíz of the Universidad Autónoma Agraria “Antonio Narro”. This line has excellent combining ability with other parental lines; however, it is susceptible to some diseases so that we are interested in improving it by using the backcross procedure. The Nepo population was used as a source population which is resistant to mildew spp. Three backcrosses and two recombinations were practiced before deriving lines and cross them with some testers. The objectives of this work were: 1. To evaluate the performance of recovered lines in combination with the original line MLS4-1, and with un-related testers, taking into account their combining ability and agronomic traits in relation to the hybrid AN-388, 2. To now the effectiveness of the backcross method to improve the MLS4-1 line. The results of this study allowed us to identify superior recovered lines that, in combination with the diverse testers, exceeded the agronomic value of thehybrid AN-388. Some recovered lines crossed with the MLS4-1 line produced excellent single crosses, indicating the possibility of getting new versions of the hybrid AN-388. Finally, we conclude that the improvement of the MLS4-1 line has permitted us to identify the best lines with higher combining ability and better agronomic traits.