In our previous study, prenatal diethylstilbestrol (DES) exposure (days 7-21 of gestation) suppressed plasma testosterone levels and histological development in the epididymis of rat offspring. In this study, we measured cell proliferation in epididymal ductules and the expression of steroid hormone receptors and 5alpha-reductase 1 in the epididymis to assess the effect of DES on epididymal development in the offspring. Prenatal DES exposure did not alter the cell division index, but suppressed the expression of androgen receptor mRNA at 15 weeks after birth, and stimulated estrogen receptor alpha mRNA at 6 weeks. These results suggest that prenatal DES exposure results in the retardation of epididymal tissue maturation by disruption of the postnatal expression of steroid hormone receptors.