Male rats with large lesions in the bed nucleus of the stria terminalis (BNST) had more intromissions preceding ejaculation (if they ejaculated at all), longer intervals between intromissions, and longer postejaculatory refractory periods than control animals. In tests for penile reflexes, BNST males were similar to control males in every respect. The copulatory deficits in BNST males are probably not mediated by a change in penile reflex potential.