Previous work from our laboratory has indicated that a direct infusion of progesterone (P) into superfusion chambers containing corpus striatum (CS) tissue fragments of ovariectomized/estrogen-treated female rats augmented amphetamine-stimulated dopamine release in vitro. In this report, we examine whether this phenomenon is also present in the male rat. Only in castrated male rats treated with estrogen were we able to demonstrate an increase in amphetamine-stimulated dopamine release in response to a direct infusion of P. Intact and castrated male rats treated with testosterone propionate or vehicle failed to show any significant differences in response to P. These results demonstrate that the CS of male rats can respond to P only if males are exposed to an estrogenic hormonal milieu and indicate an absence of a sexually dimorphic response of the CS to P.