Eight hundred and twenty five infertility patients were investigated to reassess the association between uterine mild anomaly and menstrual disorder proposed as a new syndrome by Sørensen. A hysterosalpingogram we classified the shape of the uterine cavity into 4 types: Normal uterus, T-shaped uterus, arcuate uterus and others (included septate uterus, bicornuate uterus,--), and also classified the size of the uterine cavity into 3 groups; large uterus, medium-sized uterus and small uterus. After classification of uterine shape and size, menstrual disorder in each patient was reviewed and the correlation between uterine anomaly and menstrual disorder was examined. Five hundred and twenty eight out of 770 patients (68.6%) were assigned to normal uterus, 75(7.9%) to T-shape uterus, 148(19.2%) to arcuate uterus and 19(2.5%) to others. Their incidences of menstrual disorder were 31.4%, 37.2%, 39.2% and 42.1%, respectively, and no significant difference was found among them. There were 55 patients (7.3%) with a large uterus, 655(87.2%) with a medium-sized uterus and 41(5.5%) with a small uterus. The incidences of menstrual disorder were 16.4%, 35% and 34.1%, respectively, and there was significant difference in incidence between large uterus and medium-sized uterus. The uterine fundal depression index (FDI) was used as a parameter to evaluate uterine mild anomaly. The incidences of menstrual disorder were 29.8% in the FDI-0 group, 32.9% in the FDI-1 approximately 10 group, 42.7% in the FDI-11 approximately 20 group, 45.5% in the FDI-21 approximately 30 group and 22.2% in the FDI-over 31 group. However, it was difficult to find a difference in the pregnancy rate or delivery rate among different classifications of uterine shape, size or FDI. From these results, it can be said that mild uterine anomaly is hardly associated at all with menstrual disorder clinically.