Sleep-related penile erections provide a unique opportunity to objectively study erectile physiology in man. Testosterone is one of several factors involved in normal sexual function and testosterone reduction can be achieved by administering luteinizing-hormone releasing-hormone agonists (LHRH-A). In this study, ten healthy, young adult males were administered LHRH-A or placebo for a 12-week period. Subjects taking LHRH-A had a marginally significant decline in sleep-related erection duration at week 4 and significant reductions at weeks 8 and 12. By contrast, no statistically reliable change was found for the number of erections over the course of study. Maximum circumference increase during sleep erections showed mixed results. These results indicate that, whereas androgen reduction adversely affects sleep-related erections, it does not eliminate them over a 12-week trial in healthy young adult men. Further study in a larger sample is needed. Nonetheless, these preliminary findings support androgen having an important role in sleep-related erections.