Histologic findings of endometrial tissue obtained by means of infertility studies on the first day of menstruation at Woo Sok Hospital Korea University from 1964 to 1973 were presented. Histologic findings which were agreeable with their menstrual cycle were noted in 85.4% of total 525 cases. Remaining cases revealed proliferative phase in 5.9%, endometrial hyperplasia in 0.4%, tuber culous endometritis in 1.7%, nonspecific endometritis in 0.4%, endometrial tissue with placenta in 1.2% and inadequate specimen in 5.2%