Among 37 patients with peripheral T3 lung lesions, preoperative clinical and imaging evidence was suggestive of T3 disease in 28 and of T2 disease in nine. Intraoperatively, the T2 designation was changed to T3 on the basis of adherence of the tumor to the parietal pleura. All had mediastinoscopy followed by resection and complete lymph node dissection. There were 17 lobectomies and 20 pneumonectomies. The chest wall was resected in continuity with the lung in 21 patients, and in 16 only an extrapleural resection was done. Follow-up was completed in all patients (range 2 to 14 years, median 7 years). The 5-year actuarial survival rate for all patients was 30%. As expected, the presence of lymph node metastasis affected the 5-year actuarial survival rate: N0 = 41%; N1 = 29%, and N2 = 0%. Histologic examination of the resected specimen confirmed a T3 lesion in 30 patients. The tumor was removed completely in 100% of patients whose chest wall was resected in continuity with the lung but in only 31% in whom an extrapleural resection was done. In the absence of lymph node metastasis, the 5-year survival rate of patients after en bloc resection of the chest wall was 50% compared with 33% for those with extrapleural resection (p less than 0.05). The finding of a peripheral lung tumor adherent to the parietal pleura indicates, in most instances, extension through the parietal pleura. When tumor is firmly adherent to the parietal pleura, an en bloc resection of the chest wall rather than an extrapleural dissection should be performed. This assures complete tumor removal and improves the probability of long-term survival.