The objectives were to evaluate the prognosis in resected lung cancer and to observe if perioperative blood transfusion adversely affects the prognosis. Of 208 patients with resection for lung cancer in 1978-1980, all but five were smokers: 127 had squamous cell and 81 non-squamous cell carcinoma. Stage I disease was found in 143 patients. (69%), stage II in 18 (9%) and stage IIIa in 47 (23%). Five-year survival was 52% in stage I, 29% in stage II and 7% in stage IIIa tumour; the respective 10-year rates were 37, 19 and 3%. Patients given perioperative blood transfusion (n = 95) had poorer prognosis than the non-transfused patients. According to Cox multivariate analysis, however, the relative risk of death was only slightly increased by perioperative transfusion (p = 0.07). In patients with stage II or IIIa carcinoma at diagnosis, this relative risk was 2.17 and 4.99 times higher than in stage I (p = 0.004 and p = 0.0001). Long-term survival thus was related to extent of the disease at diagnosis rather than to numbers of blood transfusions.