Patients with non–small-cell lung cancer (NSCLC) survive for variable lengths of time, even when adjustment is made for pathological stage. Numerous reports suggest that biological markers predict survival in patients undergoing surgery for NSCLC with curative intent, but many of these claims are unconfirmed or conflicting. We postulated that the use of multiple putative markers might provide greater power in predicting survival. We studied 101 consecutive patients with NSCLC who underwent exploratory thoracotomy and who were followed for at least 2 yr. We assessed mutations in the p53 tumor suppressor gene (exons 5-8) and the K-ras oncogene (codons 12 and 13) by polymerase chain reaction amplification and single strand conformation polymorphism of the product. We identified 19 K-ras mutations (all adenocarcinomas except for two) and 40 p53 mutations among the 101 cases. We also evaluated p53 protein, bcl-2 protein, c-erbB-1 protein, c-erbB-2 protein, and MIA-15-5 antigen by standard immunocytochemical techniques, and we found that all of these antigens were variably expressed. As expected, we found a strong inverse association between surgical tumor stage and survival. Of the molecular markers studied, only MIA-15-5 antigen expression correlated strongly with survival by univariate analysis (p = 0.001) and it remained a significant predictor by multivariate analysis (p = 0.01). However, in this study, overexpression of MIA-15-5 antigen predicted an improved survival, whereas the original report showed a worse prognosis (N. Engl. J. Med. 1992;327:14). We conclude the multiple cell markers are not clinically useful in predicting survival among patients undergoing surgery for NSCLC. Differences between our results and prior reports may be due to chance, to true population differences, or to other factors.