Out of 865 homosexual males who were registered by venerologists in 6 districts of the GDR highly significantly more homosexuals were born during the stressful war and early postwar period of the Second World War, i.e. between 1941 and 1947 (with a maximum of relative frequency in 1944-1945), than in the years before or after this critical period. This finding suggests that stressful prenatal (or perinatal) events may represent an aetiogenetic factor for homosexuality in human males.