The blood–testis barrier is a unique specific system between the Sertoli cells and the basal membrane of the tubuli seminiferi in the testicles that plays a major role in the immune aspects of male fertility. The first part of our presentation shows the basic structure of this intelligent system and the result of its destruction. Mainly inflammatory events, toxic agents, mechanic components, and iatrogenic factors influence the function of the blood–testis barrier, resulting in the formation of anti-sperm antibodies on the surface antigens of the human sperms, thus developing male immune infertility. Anti-sperm antibodies can influence the progressive motility and fertilizing capacity of sperm. It is still a debated issue as to the major role of anti-sperm antibodies in male infertility, especially against a background of repeated miscarriages. To examine this question we performed a prospective clinical trial to observe the suspected role of anti-sperm antibodies in repeated miscarriages. The second part of our paper demonstrates our results, showing no statistically significant impact of anti-sperm antibodies in repeated miscarriages.