An unbalanced X-autosome translocation was observed in a patient with primary amenorrhea, Turner phenotype and bilateral streak gonads. The karotype of the proposita was 45,X, -X, + der(6), t(X;6). Autoradiography and BUdR [bromodeoxyuridine] pretreatment revealed differential inactivation of the X chromosomes. Sex chromatin pattern was in good agreement with the types of the X inactivation. Further questions regarding inactivation of the human X chromosome and the related phenotypical changes are discussed.