BACKGROUND: Basaloid carcinoma of the lung has been reported as an uncommon and highly aggressive form of nonsmall cell lung cancers. Even in stage I and II of basaloid carcinoma, a 5-year survival rate of only 15% has been reported and it has been suggested that different treatment modalities for basaloid carcinoma should be considered. The aim of this study was to determine the prognostic implications of a basaloid carcinoma of the lung. METHODS: This study included a series of 291 surgically resected lung tumors, which were originally diagnosed as a poorly or undifferentiated carcinoma, a small cell carcinoma, or an atypical carcinoid. Of these, 35 basaloid carcinoma patients were identified and compared with 167 poorly differentiated squamous cell carcinoma (PDSC) patients in terms of the preoperative clinical data, the procedure performed, and the survival outcome. RESULTS: The overall incidence of basaloid carcinoma was 4.8%. The actuarial 5-year survival rate was 40.6% in patients with PDSC and 36.5% in those with basaloid carcinoma (p = 0.86). In stage I and II patients, the actuarial 5-year survival rate was 53.9% in the PDSC group and 57.2% in the basaloid group (p = 0.97). There were no differences in the recurrence rate and the relapse pattern (p = 0.584). Cox's proportional hazards model revealed that an age equal to 60 years old (hazard ratio 2.179, p = 0.000) and an advanced stage (hazard ratio 2.264, p = 0.000) were the risk factors for postoperative survival in both groups. CONCLUSIONS: Basaloid carcinoma of the lung does not have a worse prognosis than the other nonsmall cell lung cancers. Although it is obvious that a basaloid carcinoma is a unique histologic entity, it does not require a different treatment modality due to the similar clinical behavior with other nonsmall cell lung cancers.