Diagnosis of ambiguous genitalia in a newborn is an emergency that can be difficult to manage, not only because salt wasting entities must be ruled out, but also due to the importance of gender assignment before psychological gender is established. We report two cases of male pseudohermaphroditism, a true hermaphroditism and a 5-alfa-reductase deficiency. The physiology of sexual differentiation and diagnosis, as well as the management of these infants, are discussed.