We examined p53 protein expression, proliferating cell nuclear antigen (PCNA), and argyrophilic nuclear organizer regions (AgNOR), in 102 patients with surgically-treated non-small cell lung cancer (NSCLC). p53 positive cases with DO-1 were defined when more than 10% of the tumor cell nuclei were stained. Mean AgNOR count and PCNA LI were 2.80 and 40.7 and there were no significant differences of AgNOR count and PCNA LI between p53 positive and negative cases. We assessed the relationship between the p53 immunoreactivity and various clinical or pathological parameters. p53 positive rate of stage III disease (46.3%) was significantly higher than that of stage II disease (28.6%). The p53 positive rate of squamous cell carcinoma (42.1%) tended to be higher than that of adenocarcinoma (33.9%). In the survival curves of patients with NSCLC according to the p53 immunoreactivity, there was no significant difference between p53 positive and negative cases. Eight potential prognostic parameters (p53 immunoreactivity, AgNOR count, PCNA LI, sex, age, year of operation, histology, and stage) were also estimated, using univariate and multivariate analysis. In univariate analysis, PCNA LI and AgNOR count, and stage were significantly related to shortened survival. In multivariate analysis, PCNA LI, Age, and stage were independently associated with shortened survival of NSCLC patients. PCNA staining may be more useful than p53 and AgNOR staining in assessing the aggressiveness of surgically-treated NSCLC, although the most useful clinical prognostic parameter should be achieved by the combined analysis of several prognostic indicators.