We undertook a retrospective review of 100 impotent men under age 40 to determine the underlying etiologic factors in the group and to evaluate the role of surgery in their care. Although patients ranged in age from 18 to 40 (mean--32.2 years), the number of patients increased steadily with advancing years. The majority of patients (72) had vasculogenic impotence (arteriogenic--15, venogenic--46, mixed--11), followed by psychogenic (13), neurogenic (12) and other causes (4). The differential diagnosis did not correlate with age. Contributing factors were present in 76%, trauma and substance abuse being most common. Essentially equal numbers of patients were treated surgically (40) and with intracavernous injection of vasoactive agents (39). Considerably fewer had a vacuum constriction device (5), oral medication (5), psychotherapy (4), other therapy (4), and none (3). The majority of patients referred to our tertiary urologic practice for treatment of vasculogenic impotence were sent by other urologists. Although the referral source did not appear to influence the choice of treatment, it probably has accounted for the preponderance of vasculogenic impotence in this series.