Chromosomes of 40 sexually abnormal human subjects were surveyed in this study. Diagnostic and clinical features of patients are shown in Table 1, and chromosomal information obtained is summarized in Table 2. The XXY sex-chromosome constitution was detected in 6 Klinefelter's syndrome cases and the XO mechanism in a Turner's syndrome patient. Thirty-three cases clinically having sex anomalies were found to possess in each an apparently normal chromosome complement both numerically and morphologically.