The reproductive performance of 36 women who had been successfully treated for gestational trophoblastic tumors with multiple courses of cytotoxic agents including methotrexate, 6-mercaptopurine, actinomycin D, and 6-azauridine, between 1962 and 1972, has been studied in comparison with 36 patients who had spontaneously aborted a hydatidiform mole but received no treatment and a control group consisting of 36 women attending an antenatal clinic. The majority of patients who wanted further pregnancies following chemotherapy had one or more successful conceptions. The incidence of abnormal pregnancies in the treated group was higher than that of the control group. Similarly, there was a higher number of abnormal pregnancies in the untreated mole patients when compared with the control group. This suggests that patients who develop trophoblastic tumors tend to have a poor obstetric history and that this is not significantly worsened by chemotherapy.