The aim of this study was to detect the expression of the pp GalNac-T10 protein in gastric carcinoma and to investigate the role of pp GalNac-T10 in the occurrence and development of gastric cancer tissues. pp GalNac-T10 protein expression was immunohistochemically analyzed in 96 gastric adenocarcinoma tissue samples, and in 88 5-cm adjacent non-tumor gastric mucosa samples, used as controls. pp GalNAc-T10 expression in gastric cancer tissues was higher compared with that in the adjacent non-tumor gastric tissue. pp GalNAc-T10 protein expression had a significant positive correlation with histological type and degree of differentiation of gastric cancer (P<0.05). Expression in diffuse type gastric cancer was notably higher compared with that in intestinal type gastric cancer. Expression in poorly differentiated tumors was markedly higher compared with that in high and mid degree differentiated tumors. pp GalNAc-T10 protein expression was not significantly positively correlated with clinical stage, depth of invasion or lymph node metastasis (P>0.05). pp GalNAc-T10 expression is a useful indicator of tumor differentiation in gastric cancer.