Abstract: Objective: To detect the roles of PTEN and Notch1 in the occurrence and development of colorectal cancer and their mechanisms,and the correlations.Methods: The expressions of PTEN and Notch1 in 60 cases of colorectal cancer tissues and 30 casess of adjacent non-tumor tissues were detected by immunohistochemistry,and their relationships with clinicopathological parameters were analyzed.Results: The positive rate of PTEN expression in colorectal cancer tissue(58.3%) was significantly lower than that in non-tumor tissue(96.7%)(P<0.01),the differences of the differentiation degree,clinical Dukes stage,serosal invasion and lymph node metastasis between them were statistically significant(P<0.05).The positive rate of Notch1 expression in colorectal cancer tissue(45.0%) was significantly higher than that in non-tumor tissue(6.7%)(P<0.05),the differences of the differentiation degree,clinical Dukes stage,serosal invasion and lymph node metastasis between them were statistically significant(P<0.05).The PTEN expression was negatively correlated to the Notch1 expression in colorectal cancer tissue(P<0.05).Conclusions: The dysregulation of PTEN and Notch1 expressions may be associated with the occurrence and development of colorectal cancer.The expression levels of PTEN and Notch1 can provide the theoretical basis in the early diagnosis and treatment of colorectal cancer.