A double-blind, placebo-controlled crossover study was undertaken in 10 neuroleptic-treated male schizophrenic outpatients to assess the effect of coadministration of selegiline 15 mg/day for 3 weeks on their sexual dysfunction. Selegiline was not found to be effective in improving any domain of sexual functioning despite a significant decrease in prolactin levels (P < 0.05). This study emphasizes the complex nature of sexual dysfunction in schizophrenic-treated patients and the need for placebo-controlled trials for this condition.