Epidemiological research in schizophrenia is back in fashion and has taken an iconoclastic turn. Received truths about schizophrenia had a reassuring stability about them, rather like Euclidean geometry. In contrast to, and perhaps in reaction to, the frustrating nebulousness of the disorder itself, its distribution had the attributes of a universal constant: incidence and symptoms unchanging over time and across space–and between the sexes. Dissenting voices were few, but now are growing in number and volume. One sex difference, that of age at onset of schizophrenia, has been accepted since Kraepelin's time, although is still unexplained. But sex differences in incidence, course, and symptoms are now being mooted which hint at sex-dependent differences in aetiology. Much of the re-examination of this issue has sprung from the work of Jill Goldstein and colleagues at Harvard, Robin Murray, David Castle, and colleagues at the Institute of Psychiatry, as well as others, such as Mathias Angermeyer in Mannheim.