A phenotypically normal woman with a 47,XX,i(Xq) karyotype is reported. She has had two successful pregnancies monitored by prenatal diagnosis with the delivery of normal offspring. The presence of a structurally abnormal third X chromosome has not demonstrably affected this patient or her reproduction. The importance of the human X and Y chromosomes in sexual differentiation is readily apparent. Patients with anomalies of the X chromosome most frequently have clinical features of Turner's syndrome. Much less clearly defined are patients who possess additional X chromosome material. For example, triple X females are not easily distinguishable from 46,XX females. Only a few cases have been reported of patients who have a 47,XXX karyotype with the third X chromosome being structurally abnormal. This report describes a patient with a 47,XX,i(Xq) (qter leads to cen leads to qter) karyotype.