The Assaf sheep breed selection program has been implemented by Deputation of Leon since 1998. The breeding goal of the selection scheme is to increase milk production per 150d standardized lactation. The efficiency of the program has been evaluated using genetic evolution per year and different animal genetic trends. The study included connected flock information (26.721 ewes with genetic evaluation) from January 2006. The average estimated breeding values has been established as function of birth year of ewes since 1996. The genetic trend for ewes was 4.66 l/yr and the average estimated breeding values of sires were over the average of population. No genetic superiority was found for ewes with known sire (5.90 l/yr) relative to ewes with unkown sire (3.43 l/yr), showing a scarce difference in genetic quality between artificial insemination and natural service sires. Thus, it can be concluded that there has been a positive evolution of the implemented scheme, despite the improvement could has still been due to individual decisions of the breeder rather than developed scheme.