We analyzed the clinicopathologic characteristics of 140 cases of neoplasia arising in dysgenetic gonads. These 140 cases were found on a review of the medical literature published between 1953 and 1983. The age of the patients at the time of diagnosis was recorded in 133 patients and ranged from 6 months to 45 years. The mean age at diagnosis was 18 years 8 months. Thirteen (9.8 per cent) patients were below the age of 10 at the time of diagnosis. A menstrual history was recorded in 109 cases. Amenorrhea was present in 103 (94.5 per cent). A Y chromosome or Y-chromosome fragment was present in 90.7 per cent of the 119 patients who had karyotype analysis. Bilateral tumors were found in 54 instances (38.6 per cent). Thus, a total of 194 neoplasms were found. Of these 103 (53.1 per cent) were gonadoblastomas, 38 (19.6 per cent) dysgerminomas, 34 (17.5 per cent), gonadoblastoma with areas of dysgerminoma, and 19 (9.8 per cent) were of other histologic types. Patients with dysgenetic gonads and Y chromosome material are at risk for development of ovarian neoplasm. A dysgerminoma of dysgerminomatous component was present in 37 per cent of the reviewed tumors. These neoplasms have been discovered as early as 6 months of age and 9.8 per cent of the cases occurred in patients below the age of 10. Early exploration and bilateral gonadectomy should be performed in patients with gonadal dysgenesis and Y-chromosome material in their karyotype.