Hypospadias and cryptorchidism are common congenital anomalies. Recently, increases in the prevalence of hypospadias and cryptorchidism have been reported in various countries, including Japan. As male sexual differentiation is critically dependent on normal androgen concentrations, increased exposure to environmental factors affecting androgen homeostasis during fetal life (i.e. EDCs with estrogenic or anti-androgenic effects) may cause hypospadias or cryptorchidism. However, the results from the International Clearinghouse for Birth Defects Monitoring System (ICBDMS), hospital-based studies in each country and population-based studies in Japan are different, because in the present system there are some problems such as the standardization of diagnostic criteria and the difference of the time of diagnosis, we hope to improve the monitoring system method. Previous papers have reported that hypospadias and cryptorchidism were associated with maternal exposure to progesterone, estrogen, diethylstilbestrol (DES) and pesticide. However, there are few studies evaluating the quantity of endocrine disrupting chemicals, using biological samples. In the future, a well-designed epidemiological study is needed to elucidate the relation between endocrine disrupting chemicals and genital development.