Cultural influences on sex differences in clinical characteristics and symptomatology of schizophrenia were studied among 369 schizophrenic patients from the United States and Turkey. Male schizophrenics were more likely to be single, and were younger than female schizophrenics at onset of symptoms and when first diagnosed, treated and hospitalised in both cultures. Turkish male and female schizophrenics were more ambivalent, inappropriate, "silly", euphoric, depersonalised, dissociated, mute, conceptually disorganised, and exhibiting more flight of ideas and thought than American male and female schizophrenics. Irrelevant thought and stereotypic behaviour were most severe in Turkish male and American female schizophrenics. Hallucinatory behaviour was most intense in Turkish separated, divorced, or widowed female schizophrenics and American married male schizophrenics. Turkish married female and Turkish separated, divorced, or widowed male schizophrenics were most disoriented. Turkish single female schizophrenics were most mute. Turkish separated, divorced, or widowed male schizophrenics showed most intense stupor behaviour.