Twenty-four anatomically intersexed patients with ambiguous external genitalia are described. All were studied in the Soviet Union. One patient was a true hermaphrodite, three had mixed gonadal dysgenesis, nine were male hermaphrodites with testes in various stages of dysgenesis, and 11 were females with congenital adrenal hyperplasia. In several cases, the appearance of the genitalia was markedly incongruent with the assigned sex, e.g., a woman with a 7-cm phallus and a boy with a 1.5-cm phallus. With two partial exceptions, gender identity corresponded to the sex assigned at birth. In same-aged patients with the same clinical features and almost identical appearance of the external genitalia, but assigned to different sexes, gender identity corresponded to neonatal sex assignment. These cases demonstrate that gender identity is not determined prenatally by biological influences. Gender identity is postnatally learned and determined by sex assignment in infancy and the resultant socialization experiences.