The difference between the endometrial cancer incidence in Japanese and Finnish women (lower and higher incidence, respectively), was evaluated on the basis of data from cases of endometrial cancer, cervical cancer and benign gynecological disease in both countries. The comparison took into account the various personal and clinical characteristics of these cases. In endometrial cancer, Japanese and Finnish women had similar characteristics except for the age at first delivery, the age at last delivery and obesity. However, obesity in postmenopausal women in the two countries was similar. Common factors in the two countries included few pregnancies and deliveries, nullipara and single women. In cervical cancer, no difference between the characteristics of Japanese and Finnish women was found except that Japanese women had a higher frequency of pregnancy. In benign diseases, characteristics were similar to those of endometrial cancer in Finnish women, but this was not the case in Japanese women. These facts may indicate the number of Finnish women with endometrial cancer risk factors is greater than the number of Japanese women with these risk factors. This was thought to account for the difference in the incidence of endometrial cancer.