Eleven cases of true hermaphroditism (eight previously reported) studied at The Johns Hopkins Hospital are presented. The two most recently observed patients had what is to be considered an appropriate endocrine evaluation. This includes karyotyping, and measurement of 24-hour urinary 17-ketosteroids, gonadotropins, plasma testosterone, dihydrotestosterone, and all their precursors before and following a human chorionic gonadotropin stimulation test, and a sexual skin biopsy for androgen receptor binding and 5 alpha-reductase activity. The differential diagnosis of true hermaphroditism is discussed and an approach to gender assignment is presented.