A regimen of multiple intermittent intensive doses of chemotherapy (chiefly 5-fluorouracil) was used in a series of 806 women with choriocarcinoma and malignant mole. The rate of complete remission of choriocarcinoma was 78.6%, and approximately 85% of the patients survived for more than 5 years. From 1962 through 1982, pulmonary metastatic choriocarcinoma was found to be resistant to chemotherapeutic agents in 43 of these patients; they subsequently underwent lung resection. There were no postoperative deaths, and the 5-year survival was 50%. These are relatively good results for patients with long-standing and widely disseminated choriocarcinoma. Human chorionic gonadotropin titer in urine and blood and variations of lung shadows are important criteria in selecting candidates for lung resection. For preservation of lung function, simple lobectomy is the first choice. Better long-term survival was obtained in patients who had a solitary lung lesion on admission without other major organ metastases and in those in whom the lung lesion was well encapsulated and became necrotic after chemotherapy.