Objective To study the relation along p53, p21 protein, p21 gene and their clinical significances in 40 gastric comparing with normal gastric tissues.Methods In this study, the p53 and p21 protein were investigated in 40 gastric carcinomas using IHC(Immunohistochemistry). At the same time, the possible presence of p21 gene mutation was also analyzed by silver staining PCR-SSCP method.Results The abnormal expression of p53 and p21 protein occurs only in gastric carcinoma; The expression of p53 protein and p21 is not related to the clinico pathological features. There was relationship between the expression of p53 protein and p21 protein. In 40 cases of gastric carcinoma, single strand conformational polymorphism of PCR product for p21 gene in tumor tissue shows no altered band or mobility shifting.Conclusion The abnormal expression of p53 and p21 protein occurs only in gastric carcinoma and is not related to the clinicopathological features. The expression of p21 protein is related to that of p53 protein. The mutation of p21 gene was not found in all of 40 tumor specimens. This suggests that p21 alteration in gastric carcinoma is caused through the inactivation of p53 protein rather than through intragenic mutation of the p21 gene itself.Using drugs which can stimulate p21 gene is a new method to cure gastric cancer with mutation-p53 protein.