Of 127 patients with hydatidiform mole in southern Connecticut, 34 (28%) received chemotherapy for persistently elevated human chorionic gonadotropin (hCG) titers. An hCG regression curve was found to be useful if not mandatory for following patients. Excess uterine size, theca lutein cysts, uterine bleeding, and histologic trophoblastic hyperplasia were relative discriminators of the need for chemotherapy. In the absence of metastases, an hCG titer was the only valid discriminator for initiating chemotherapy, provided the patient could be followed consistently and reliably. The indications for initiating chemotherapy are discussed. Early diagnosis and close follow-up were associated with low morbidity. Five of 6 patients with metastatic disease were referred from outside the center.