Mutations in the p53 tumor suppressor gene are considered to play an important role in the carcinogenesis of pancreatic cancer. The present study was designed to assess the clinicopathological significance of the expression of p53 protein in human pancreatic cancer. A total of 64 specimens of pancreatic cancer (44 primary and 20 metastatic lesions) were obtained by surgery in our department between 1982 and 1995, and p53 protein was stained using an immunohistochemical staining method (strepto-avidin-biotin complex method) with 2 kinds of anti-p53 monoclonal antibodies (DO-1 and PAb240). DO-1-p53 was usually stained in the nucleus of cancer cells and was positively expressed in 35 out of 64 specimens (54.7%): 21 out of 44 primary lesions (47.7%), and 14 out of 20 metastatic lesions (70.0%). On the other hand, PAb240-p53 was stained in both the nucleus and cytoplasm in 45 out of 64 specimens (70.3%): 33 out of 44 primary lesions (75.0%) and 12 out of 20 metastatic lesions (60.0%). The survival rate of the patients with DO-1-p53 (+) pancreatic cancer after pancreatectomy was significantly lower than that of patients with DO-1-p53 (-) pancreatic cancer. On the other hand, there were no significant implications of PAb240-p53 protein expression on survival after pancreatectomy. With regard to the clinicopathological characteristics, the rate of DO-1-p53 protein expression was significantly higher in elderly patients (> or = 65 y.o.). As a result, DO-1-p53 protein expression may be a beneficial prognostic factor for patients with pancreatic cancer, and it is a factor independent of the stage and other clinicopathological factors.