In a consecutive clinical series of 538 subjects with primary mood disorders the male:female differences were most skewed (1:4) in recurrent unipolars, 1:2 in single episode and bipolar I subtypes, and about even (1:1) in bipolar II. The sexes did not differ in age at onset of depression, stressors preceding index episodes, endogenous features, psychotic symptoms, suicide attempts, and rates of chronicity. Females had lower mean number of hypomanic, and higher mean number of depressive, episodes. Females also exhibited more anxiety and somatisation, and were more likely to endorse psychopathological items on self-report instruments, which were not reflected in objective measures. Finally, they were more likely to have been admitted to hospital. These gender differences could in part be explained by the higher prevalence of the depressive temperament in women, and of the hyperthymic temperament in men.