Objective:To investigate expression of cyclinD1 and p21WAF1 and their relationship with multistage process of colon carcinogenesis.Methods:Immunohistochemical staining was performed with SP assay on archival materials from 40 colorectal carcinomas,28 colorectal adenomas,and 14 normal mucosa,cyclinD1 and p21WAF1 expression were compared.Results:The positive staining rate for cyclinD1 in colorectal adenomas and carcinomas is 92.9% and 67.5% respectively,which are both higher than that in the normal mucosa (35.7%) (Padenoma＜0.01，Pcarcinoma＜0.05) and the expression of cyclinD1 is not correlate with differentiation and lymph node metastasis of colorectal carcinoma.The positive stainimg rate for p21WAF1 in normal mucosa (92.9%) is higher than that in colorectal carcinoma(37.5%) (P＜0.01) and the expression of p21WAF1 is correlate with differentiation and lymph node metastasis of colorectal carcinonma.Conclusions:The aberrant expression of cyclinD1 and p21WAF1 is a common event during multistage process of colon carcinogenesis.