Selections horse programs are mainly focused on their usability in sports or exterior traits. Fertility is often neglected, even though i tis a trait of great economic importance. Fertility levels are affected by both genetic and enviromental factors. The fertility heritability coefficients of both mares and stallions are low, however fertility trits can be effectively selected using breeding values.A large database containing both phenotypic and pedigree data is needed to develop a genetic evalution of fertility traits. Globally the availability of database sis a limiting factor, which i salso the reason why the estemation of genetic parametrs is difficult. Another reason is low number of offspring and the long generation interval of horses. The reproductive level of horses can also be increased by using reproductive biotechnology.