[Phenotypically a boy, genotypically a girl; the 46,XX male syndrome]

A three and a half years old boy with obesity, a small penis, and cryptorchism appeared to have a 46,XX karyotype in cultured peripheral lymphocytes. The clinical features of this rare syndrome and theories of etiology of 46,XX male subjects are discussed. Furthermore we stress the importance of thorough investigation in case of non-palpable testicles in an individual having a penis.