The olfactory epithelium and the afferent nerve fibers to the olfactory lobes were destroyed in one group of rats, while in another the olfactory peduncle was destroyed bilaterally. Following either operation the animals showed an impaired sexual behavior. They mounted, intromitted and ejaculated at one testing occasion but not at another, and when ejaculating, the latencies were prolonged compared to intact control animals. No recovery was seen during the 4-month period of post-operative testing. It was concluded that the sexual failure was due to deficient sensory input and not to brain damage.