Eighty-four patients with pulmonary metastases from gestational choriocarcinoma were treated at the Catholic Medical Center between August, 1985 and August, 1991. Among these 13 patients underwent thoracotomy with resection of pulmonary lesions and the results obtained were follows. 1] The ages of the patients ranged from 26 to 47 years, with a mean age of 31 years. 2] The frequency of chemotherapy before operation ranged from zero to 46, with a mean frequency of 13.6. 3] Four patients were operated upon for a solitary metastasis of the lung; 6 patients, for unilateral multiple metastases and 3 patients, for bilateral pulmonary metastases. 4] Eight patients underwent wedge resection; 1 patient, segmentectomy; 2 patients, lobectomy; 3 patients, open lung biopsy. The lung lesions of eleven patients showed hemorrhagic necrosis[among these, 2 patients combined with pulmonary tuberculosis]; one was non-necrotic choriocarcinoma; another one was metastatic lung carcinoma from endocrine cancer of unknown origin. 5] Among twelve patients who had managed with chemotherapy before thoracotomy three patients were in remission; among 13 patients who had undergone thoracotomy 6 patients were in remission. 6] The median survival time of these patients was 25.8 months with 3 postoperative deaths. Subsequently, in the patients with pulmonary metastases from choriocarcinoma, if the primary tumor is under control, there are no other metastases, and the patients should be able to tolerate the planned operation, it is necessary to undergo aggressive thoracotomy for diagnostic purposes; for therapeutic purposes only when the pulmonary lesion is the only remaining source of increased hCG excretion; for reduction of tumor volume to shorten hospitalization or to reduce the quantity of drugs.