Abstract: Objective To evaluate the relationship between the overexpression of cyclin D1 and Ras in the progression of gastric carcinogenesis. Methods The overexpression of cyclin D1 and Ras were studied in gastric carcinoma,precancerous lesions by immunohistochemical technique. Results The overexpression of cyclin D1 and Ras were observed in none of the 20 normal gastric mucosas.The positive rates of cyclin D1 and Ras were 59.2% and 57.1% in gastric cancer,respectively,and there was a significant correlation between the overexpressions of the two oncogenes (P<0.05).Cyclin D1 overexpression closely correlated to size of tumor (P<0.05) and adenocarcinoma (P<0.05),while Ras overexpression inversely correlated to poor differentiation (P<0.05),but closely correlated to intestinal carcinoma (P<0.05).The overexpression of cyclin D1 and Ras had no correlation with lymph node status (P>0.05),depth of invasion (P>0.05),and clinicopathologic stage (P>0.05). Conclusion The overexpression of cyclin D1 cooperated with activated ras in the process of malignant changes in the gastric mucosa and showed no prognostic significance.