BACKGROUND: To explore frameshift mutations in the Bax and TGFβRII genes and the relationship between frameshift mutations and microsatellite alterations in lung cancer. METHODS: Frameshift mutations and microsatellite alterations were detected in 50 primary lung cancer tissues by PCR,8% denature polyacrylamide gel electrophoresis and silver staining. RESULTS: Bax gene (G)₈ frameshift mutations were detected in 12 cases (24%,12/50),and all were base deletion mutations.Bax frameshift mutations correlated with microsatellite alterations (P<0.05).TGFβRII (A)₁₀ frameshift mutations were not found. CONCLUSIONS: Bax gene frameshift mutations are found in lung cancer,and closely correlate with microsatellite alterations.Bax gene and microsatellite might play a certain role in carcinogenesis of lung cancer.