The bcl-2 gene product (bcl-2 protein, BCLP) prevents apoptotic cell death. Via a 14;18 chromosomal translocation, BCLP is overexpressed in most follicular lymphomas as well as some other non-Hodgkin's lymphomas, and it has also been documented in other nonlymphomatous malignancies. To address the possible prognostic value of this marker in predefined subsets of non-small cell lung carcinoma (NSCLC), the authors studied 126 T1N0M0 cases seen between the years 1986 to 1991 at our institution. Patients were treated by lobectomy (105 cases) or wedge excision (21 cases) with negative margins; neuroendocrine carcinomas of all grades were specifically excluded. The mean follow-up period was 39 months. Immunostaining for BCLP was done using a monoclonal antibody (clone no. 124; DAKO, Carpinteria, CA), and the avidin-biotin-peroxidase complex (ABC) technique. The study cases included 73 adenocarcinomas (ACs) as well as 40 squamous cell (SCC), five adenosquamous (ASC), and eight large cell/poorly differentiated (LCC) carcinomas. As assessed with the Kaplan-Meier method, overall survival was 64% at 5 years (66% AC vs 59% SC). BCLP was detected in 47 of 126 cases (37%) including 32 AC (44%), 10 SCC 925%), two ASC (40%), and three LCC (38%). No significant difference in 5-year survival was noted in a comparison of all cases with BCLP expression (63%) and those without (59%). There was, however, a significant difference in the survival of grade 1 BCLP(+) cases, when compared with grade 2 or 3 BCLP(+) cases (P = .01). A nonstatistically significant trend toward increased survival was observed in BCLP(+) SCC cases (66% 5-year survival in BCLP[+] vs 45% in BCLP[-] [P = .11]). Proportional hazards analysis failed to disclose significant independent risk factors. These data suggest that bcl-2 protein immunoreactivity has limited prognostic value in the pathological evaluation of NSCLC.