The aim of this study was to determine the expression of Bcl-2 gene and prognostic importance of Bcl-2 expression in paraffin embedded blocks of patients diagnosed with non-small cell lung cancer (NSCLC). This study included the retrospective analysis of overall 46 patients diagnosed with NSCLC in our clinic between 1996 and 1999. In 16 (34.8%) patients, the diagnosis was made on biopsy of bronchial mucosa and in 30 (65.2%) patients, on materials obtained by surgical resection (lobectomy and pneumonectomy). We reviewed the sections 4-6 microns in size and stained with Hemotoxylin-Eosine (HE) obtained from paraffin embedded blocks and fixed by 10% formalin. These sections are transferred on to slides covered with poly-L-lysine, then de-paraffinization was made. In all cases, immunohistochemical staining with Bcl-2 antibodies was performed. Positive staining was observed in 9 (19.6%) patients, but not in 37 (80.4%) patients. Out of 32 cases with squamous cell tumor, 8 (25%) were observed to have positive staining in their sections, but 24 (75%) were not so. No staining was observed in 11 cases whose cell type was adenoma and two cases whose cell type was adenosquamos (100%). Staining was present in the section of one case with large cell (100%). Median survival time was 36.6 months in cases in which staining was observed and 6.10 months in cases in which staining was not observed, with a significant difference (p< 0.05). In conclusion, the rate of survival was higher in cases in which staining was present.