ObjectiveTo investigate the expressions of CD133 and CD44 protein in primary lesions of gastric cancer and its clinical significance. MethodsThe expressions of CD44 and CD133 protein in gastric cancer tissues of 100 patients with gastric cancer were detected by immunohistocheimcal stainings.The relation between the expressions of CD44 and CD133 protein and the clinicopathologic characters were analyzed. ResultsBoth CD44 and CD133 protein were expressed on the cell membranes.No correlation were found between CD44/CD133 and the clinicopathologic parameters include gender and age (P > 0.05), but the positive expression rate of CD44/CD133 with diameter>5 cm was significantly higher than that tumor with diameter≤5 cm (CD44 P=0.150;CD133 P=0.056), and correlated with the tissue differentiation (CD44 P=0.008;CD133 P=0.007), vascular invasion (CD44 P=0.043;CD133 P=0.023), lymphatic vessel invasion (CD44 P=0.020;CD133 P=0.044), lymph nodes metastasis (CD44 P=0.002;CD133 P=0.004), inva-sion depth of tumor (CD44 P=0.006;CD133 P=0.021), and pTNM stage (CD44 P=0.034;CD133 P=0.001).No correlation were found between the co-expression of CD44 and CD133 protein and the clinicopathologic parameters include gender, age, tissue differentiation, and vascular invasion (P > 0.05), but the positive co-expression rate of CD44 and CD133 with diameter>5 cm was significantly higher than that tumor with diameter≤5 cm (P=0.010), and correlated with lymphatic vessel invasion (P=0.003), lymph nodes metastasis (P=0.045), invasion depth of tumor (P=0.041), and pTNM stage (P=0.049).The Spearman rank correlation analysis showed that there was positive correlation between the expressions of CD44 and CD133 protein (r=0.207, P=0.039).Univariate analysis showed that lymph nodes metastasis (P < 0.001), pTNM stages (P=0.013), CD44 protein expression (P=0.005), CD133 protein expression (P=0.002), and co-expression of CD44 and CD133 protein (P < 0.001) were significantly correlated with 3-year survival rate of pati-ents with gastric cancer respectively.Logistic regression analysis revealed that lymph node metastasis (P=0.038) was independent risk factor for co-expression of CD44 and CD133 protein.Multivariate analysis with the Cox regression models showed that co-expression of CD44 and CD133 protein (P=0.003) and lymph node metastasis (P=0.006) were significantly associated with poor prognosis. ConclusionsCD44 and CD133 protein may be considered as robust cancer stem cell markers in gastric cancer.The co-expression of CD44 and CD133 protein is the independent prognosis factor for gastric cancer and strongly associated with poor prognosis when they are expressed more high.