Amplification of the c-myc gene has been reported in non-small cell lung cancer (NSCLC). We performed dual color fluorescence in situ hybridization (FISH) to detect amplifications of the c-myc gene on chromosome 8 to evaluate the relationship between these possible abnormalities and pathological stage. Tumor tissue samples were obtained from 29 patients of NSCLC in Stage I (n=15) and III (n=14) who underwent lobectomy at Saitama Cancer Center. Samples were analyzed for chromosome 8 centromere and c-myc gene by dual color FISH. The numerical aberration rate of chromosome 8 was 36.8±20.3% in Stage I and 40.6±24.8% in Stage III. The amplification rate of c-myc gene was 48.3±15.2% in Stage I and 57.4±17.0% in Stage III. There was a significant difference in the numerical aberration rate of chromosome 8 between patients who survived for 5 years or more (28.8±17.5%) and those who survived less than 5 years (44.7±23.1%). The amplification rate of c-myc gene was not different between patients who survived more and less than 5 years survival, and who survived more and less than 3 years. The 5 year-survival rate in patients who showed 40% or more of chromosome 8 aberrations (n=13) was 15.4%, which revealed significantly less than that of patients who showed less than 40% of aberrations (n=16) (56.3%). There was no difference between the 5 year-survival rate in patients whose amplification rates of c-myc gene were equal or more than 50% (n=16) and less than 50% (n=13) (25.0% and 53.9%). The rate of chromosome 8 aberrations and the c-myc gene amplification rate were not correlated with pathological stage. However, the rate of chromosome 8 aberration showed correlation in terms of longevity of survival rate, therefore we considered the rate of chromosome 8 aberration to be an additional prognostic factor of patient with NSCLC. (J Nippon Med Sch 1999 ; 66 : 107-112)