A 25-year-old male hermaphrodite with the sex chromosome constitution of 46,XX is reported. Clinical, endocrinological, pathological and cytogenetical studies are presented and discussed in comparison with findings in the so-called XX males reported in the literature. Some theories to explain the paradoxical occurrence of a testis in XX males and XX male hermaphrodites are mentioned and a possible aetiological relationship between these XX male syndromes and Klinefelter's syndrome is suggested.