Subacute sclerosing panencephalitis can no longer be regarded as a rare disease in all parts of southern Africa. Information derived from a third postal survey added to that from our own experience in Cape Town has brought to light 116 cases; 61 of the patients came from the Cape Province; 40 from the Transvaal and the remaining 15 from the other regions. This unequal distribution and the high prevalence in the Coloured community are important factors in any attempt to understand the epidemiology and the pathogenesis of this serious complication of measles