Modern breeding programs use boars housed at insemination stations, where high quality and levels of management, health and biosecurity are guaranteed. Boars in natural breeding are not given such attention in terms of health. It is important to realize that the boar is not only a source of genetic progress, but is also one of the factors that influence the reproductive efficiency of the breeding. Great attention needs to be paid to the selection of suitable boars, especially for use at insemination stations. The intensity of use of boars at insemination stations is much higher than boars in natural breeding. Proper care, nutrition and housing of breeding boars affect the fertility of the entire herd of sows.