In 1950, Seiler and associates1 reported on 10 patients on whom pulmonary resection had been carried out at the Mayo Clinic in an attempt to eradicate metastatic tumors of the lungs. Hood and co-workers,2 in 1955, added 33 more patients to the series. One of the latter series was excluded later because what was considered earlier as a metastatic ovarian carcinoma is now believed to have been a second primary tumor (alveolar-cell carcinoma). The current study is an extension and continuation of the two previous ones. Its purpose is to bring the material up to date by presenting information on more recently treated patients and later follow-up data on the previous patients. By this means it is hoped to assess further the status of resection in the treatment of metastatic malignant pulmonary lesions. General Data in Present Study By the end of 1956, a total of 96 patients