A patient with an apparently normal 46, XY karyotype, suffering from pure gonadal dysgenesis and of short stature was investigated. The patient, who was growth retarded, was a 30-year-old married Japanese woman with a history of primary amenorrhea and infertility with a weight of 42 kg and a height of 146 cm. She has a phenotypically and karyotypically normal dizygotic twin brother with normal development. Southern-blot and polymerase chain-reaction analyses revealed no apparent deletions in the patient's Y chromosome, including the sex-determining region Y (SRY). The DNA sequencing of the SRY gene showed a 100% nucleotide sequence identity with the reported cloned sequence. Sex reversal in the present case may be due to mutation at a locus other than SRY in the sex determining pathway, a gene potentially involved in the determination of human constitution.