• Evidence concerning pharmacological effects on human sexuality suggests that dopaminergic receptor activation may be associated with penile erection. Erection also appears to involve inhibition of α-adrenergic influences and β-adrenergic stimulation plus the release of a noncholinergic vasodilator substance, possibly vasoactive intestinal peptide. Ejaculation appears to be mediated primarily by α-adrenergic fibers. Serotonergic neurotransmission may inhibit the ejaculatory reflex. An understanding of the neurobiological substrate of human sexuality may assist clinicians in choosing psychotropic agents with minimal adverse effects on sexual behavior and may also contribute to the development of pharmacological interventions for sexual difficulties.