The role of surgical treatment of non-small-cell carcinoma of the lung is controversial. Surgical therapy of small cell carcinoma of the lung has been the subject of criticism for two decades - in contrast to our opinion about the important role of initial surgical therapy in limited disease of this type of lung carcinoma. In a review of the results of surgical therapy in 109 patients with undifferentiated small cell carcinoma of the lung in the period from 1962 to 1979 and an attempt to define the role of the curative effect, we report on 109 thoracotomies after negative preoperative mediastinoscopy and exclusion of hematogenous spread of the cancer. The resection rate (94/109) was considerably lower than in differentiated lung carcinoma. Pneumonectomy (40%) and extended pneumonectomy (27%) were more frequently performed for small cell carcinoma than for differentiated tumors; thus, the rate of lobectomy and segmental resection (28/94 = 30%, and 3/94 = 3%, respectively) was low. When we included the postoperative lethality in the calculation rather than using the life-table method, we found in a follow-up study of 99% of the patients who had undergone resection, in absolute numbers, 3-year survival in 21/93 patients (23%). In the different stages I, II, and III, we noted 3-year survival rates of 32%, 25%, and 14%. Correlation to the N and T stages was N0 (10/29) 35%; N1 (6/34) 18%; N2 (5/30), 17%; N1 + 2 (11/64) 17%; T1 (11/28) 39%; T2 (8/35) 23%; T3 (2/30) 7%; and T2 + 3 (9/34) 14%.(ABSTRACT TRUNCATED AT 250 WORDS)