Two sisters, ages 18 and 25, presented with primary amenorrhea and underwent clinical, hormonal, cytogenetic, and pathologic evaluation. Both were of normal stature and lacking of somatic stigmata. Both patients had normal 46,XX karyotype on peripheral blood. Streak gonads were seen in both patients and a rather scanty number of primordial follicles was found in one patient. FSH, LH, and urinary estrogens were consistent with streak gonad syndrome. Autosomal recessive inheritance has been suggested in familial aggregates with XX gonadal dysgenesis.