The reproductive organs of 20 Estonian Holstein Breed (EHF) cows and three heifers, culled because of infertility, were studied by palpation per rectum and ultrasonography. In addition, pathoanatomical and pathohistological studies were carried out after slaughtering. The pathohistological study revealed that small cysts often (12 animals) existed in culled cows, whose diameter was less than 2.5 cm. These cysts were frequently accompanied by changes in secondary and Graafi follicles, rete ovarii, ovarian stroma, and the endometrium. Three cows had follicular cysts in the ovaries, which were 25-35 mm in diameter. Two cows revealed luteal cysts in the ovaries; one of them had vaginal prolapse. Four animals (one heifer and three cows) manifested tumours or tumour-like malformations: ovarian endosalpingiosis, germ and stromal cell tumour, oviductal myolipoma, and haemangiosarcoma in the uterine blood vessels. One heifer had been culled because of two abscesses in the vaginal wall close to the cervix and another had chronic endometritis. The research findings indicate that the most common cause of infertility in the culled cows was cystic degeneration in ovaries (85%), accompanied by pathological changes elsewhere in the reproductive organs. We claim that these changes are responsible for the low pregnancy rate after the treatment of ovarian cysts. The second most common reason was genital tumours (15%). In heifers, infertility is rare and its causes are heterogeneous.