Abstract: A highly rapid, sensitive and specific method was used for measuring the expression of the DCC gene in clinial samples, based on the polymerase chain reaction. The PCNA expression in colorectal carcinoma tissues was also measured by immunohistochemistry technique. The results showed:（1） There was a normal mRNA expression in 42 colorectal mucosas samples; one out of 9 （11.1%） and 20 out of 33（60.6%） cases lost of DCC gene mRNA expression in adenomas and adenocarcinomas respectively. （2）The lack of DCC gene mRNA expression was closely related with degree of tumor differentiation, depth of invasion of the bowel wall and metastasis（P ＜0.01）. （3）The colorectal carcinomas that lost of DCC mRNA expression have revealed a higher PCNA index （P ＜0.001）. The present study suggests that measuring of DCC mRNA expression is very useful to judge the degree of malignancy, invision and metastasis of colorectal cances. The machinism that DCC gene influences the colorectal carcinoma expressing type may be the loss of its ability in inhibitting cell proliferation when it is inactived.