Sexual and endocrine function in a geographically defined population of male patients receiving depot neuroleptic medication were studied (n = 119). It was predicted that psychosexual arousability would be reduced in this patient group, perhaps because of the endocrine effects of medication. Arousability was measured in 63 patients (53% of the population) using a validated questionnaire of sexual function for which normative data were available (Sexuality Experience Scales, SES 2). Blood levels of prolactin, testosterone and gonadotrophins were assayed. Physical sexual dysfunction was common, as was endocrine dysfunction. However, the sample's mean score on the global arousability scale was not significantly different from the normative mean. Arousability was negatively correlated with age and positively correlated with frequency of spontaneous penile erections, but not significantly correlated with endocrine variables or exposure to neuroleptic medication. These results suggest that sexual arousability in response to imagined or audio-visual erotic stimuli is surprisingly unimpaired in medicated male patients suffering from chronic mental illness.