A survey of five group practices in South London identified 60 male patients currently undergoing treatment for epilepsy. Fifty-four agreed to participate in a detailed enquiry into aspects of their sexual activity and behaviour. Anterior pituitary and sex-hormone levels were measured. The epileptic patients were characterized by low levels of sexual activity and interest. Temporal-lobe and non-temporal-lobe epileptics were indistinguishable in these respects, but when the latter group was further subdivided into primary generalized epilepsy and focal non-temporal lobe epilepsy, the focal groups (both temporal lobe and non-temporal lobe) were more impaired. Hormonal analysis confirmed earlier hospital-clinic-based reports. In the epilepsy group, plasma free testosterone and percentage free testosterone values were decreased, sex hormone binding globulin, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were increased compared to values in a normal healthy population. As association between the behavioural and hormonal indices of hyposexuality was shown, particularly for LH, but this was less apparent than in previous work.