AIM: To investigate the clinical and pathological significance of altered retinoblastoma (Rb) encoding protein (pRb) in gastric carcinoma.METHODS: Expression of altered pRb was analyzed in 91 patients with gastric adenocarcinoma by immunohistochemistry.RESULTS: Sixty-five percent (59/91) of the tumors were positively stained and the staining in tumor nuclei of gastric carcinoma ranged 0%-90%. Moreover, strong expression of altered pRb was found in 35% (6/17),24% (5/21), 17% (8/46) and 0% (0/7) of T1, T2, T3 and T4 gastric carcinomas, respectively. Altered pRb expression was inversely correlated with the depth of tumor invasion (P = 0.047). Degree of immunoreactivity had no significant correlation with tumor grade, node metastasis and distant metastasis. In terms of prognostic significance, univariate analysis showed that poor differentiation [41 (66.1%) vs 34 (42.5%) P = 0.051],advanced tumor stage (P ＜ 0.001) and weakly altered pRb expression [17 (80.5%) vs 58 (49.6%) P = 0.044]were associated with worse prognosis in these patients.However, multivariate analysis revealed that advanced tumor stage was the only independent poor prognostic factor (P ＜ 0.001).CONCLUSION: The mutation of Rb gene is frequent in gastric carcinoma. The expression of altered pRb inversely correlates with tumor invasion and is not an independent prognostic marker in gastric adenocarcinoma