AIM:To assess the diagnostic value of using magnifying chromoendoscopy combined with immunohisto-chemical staining of proliferating cell nuclear antigen (PCNA)and p53 in the detection of gastric precancerous lesions. METHODS:Ninety-five patients who were treated for abdominal discomfort,abdominal pain,bloating,and acid reflux at our hospital from January 2010 to December 2011 were included in the study.An ordinary gastroscopic procedure was initially performed to select the lesions.All subjects underwent magnifying chromo-endoscopy to observe morphological changes of gastric pits.Biopsies were then taken from each area of interest and sent for pathological examination and detection of PCNA and p53 expression by immunohistochemistry. An immunoreactivity score for each lesion was calcu-lated.Based on immunoreactivity scores,immunohisto-chemical staining was then considered. RESULTS:Compared to intestinal metaplasia,gastric pits were more diverse in size,more irregular in shape, and more disorderly in arrangement in moderate and severe dysplasia.PCNA and p53 expression was sig-nificantly higher in precancerous lesions(intestinal metaplasia and dysplasia)than in chronic gastritis. PCNA expression showed an upward trend in types A-F pits.The number of cases that showed strong PCNA positivity increased significantly with an increase in the severity of lesions.Rank sum test for independent samples showed that p53 expression was significantly higher in types E and F pits than in types A-D pits(H =33.068,P=0.000).Rank sum test for independent samples showed that PCNA expression was significantly higher in types E and F pits than in types A-D pits(H =31.791,P=0.001). CONCLUSION:The presence of types E and F pits,in which p53 and PCNA are highly expressed,is highly sug- gestive of the occurrence of early cancer,and patients developing these changes should be closely followed. METHODS: Ninety-five patients who were treated for abdominal discomfort, abdominal pain , bloating, and acid reflux at our hospital from January 2010 to December 2011 were included in the study. An ordinary gastroscopic procedure was initially performed to select the lesions. All subjects underwent magnifying chromo-endoscopy to observe morphological changes of gastric pits. then taken from each area of ​​interest and sent for pathological examination and detection of PCNA and p53 expression by immunohistochemistry. An immunoreactivity score for each lesion was calcu-lated. Based on immunoreactivity scores, immunohisto-chemical staining was then considered. intestinal metaplasia, gastric pits were more diverse in size, more irregular in shape, and more disorderly in arrangement in moderate and severe dysplasia. PCNA and p53 expression was sig-nificantly higher in precancerous lesions (intestinal metaplasia and dysplasia) than in chronic gastritis. PCNA expression showed an upward trend in types AF pits. PCNA positivity increased significantly with an increase in the severity of lesions. Rank sum test for independent samples showed that p53 expression was significantly higher in types E and F pits than in types AD pits (H = 33.068, P = 0.000) .Rank sum test for independent samples showed that PCNA expression was significantly higher in types E and F pits than in types AD pits (H = 31.791, P = 0.001). CONCLUSION: The presence of types E and F pits, in which p53 and PCNA are highly expressed , is highly sug- gestive of the occurrence of early cancer, and patient developing these changes should be closely followed.