Here we aimed to first investigate the clinical value of combined detection of MG7-Ag and COX-2 (cyclo-oxygenase 2) in prediction of advances in gastric precancerous lesions. Immunohistochemical analysis was used to examine the expression of MG7-Ag and COX-2 in 396 cases of patients with gastric precancerous lesions, including 66 cases of atrophic gastritis, 106 cases of intestinal metaplasia, 174 cases of low-moderate-grade dysplasia and 50 cases of high-grade dysplasia. The relation of MG7-Ag and COX-2 staining with various clinicopathological features was analysed by follow-up study. The positive rates of MG7-Ag and COX-2 were increased gradually from atrophic gastritis (21.2%, 28.8%), intestinal metaplasia (36.8%, 44.3%), low-moderate-grade dysplasia (51.4%, 58.6%) to high-grade dysplasia (72%, 80%). Double positive staining of MG7-Ag and COX-2 in gastric precancerous lesions had an increased risk of precancerous progression over 22 times, compared with negative ones. However, the expression of MG7-Ag and COX-2 was not significantly correlated with age and gender of patients. MG7-Ag and COX-2 might play an important role in the process of carcinogenesis and progression of gastric cancer. Combined detection of MG7-Ag and COX-2 was of value of predicting early gastric cancer from precancerous lesions.