Transplacental exposure to diethylstilbestrol (DES) causes morphological and functional changes including the disruption of follicular maturation in murine ovaries. Since the function of ovarian sympathetic nerves is thought to be related to the follicular maturation, we examined changes in the distribution pattern of the sympathetic nerves between prenatally DES-exposed rat ovaries and normal controls using immunohistochemistry of tyrosine hydroxylase (TH). In the DES-exposed ovaries, the TH-positive nerve innervation was poor and the innervation density was reduced to about half as compared to that in the controls. Simultaneously, follicular maturation was disrupted in the DES-exposed ovaries. These findings suggest that the prenatal DES exposure inhibited the development of ovarian sympathetic nervous system, which might be closely associated with the disruption of follicular maturation.