There are many hypotheses on the increase of male infertility. The phenomenon is believed to be connected with the presence of substances with hormonal activity – xenoestrogens in human environ- ment. The substances are divided into two groups: man made substances and components occurring naturally – phytoestrogens. Steroids influence not only male and female reproductive systems but also development and function of another tissue. Therefore, this is very important to list of substances with hormonal activity, their potency of acting, the way of expositions.