ObjectiveTo explore the expression of chloride intracellular channel protein 1 (CLIC1) protein in the matched colorectal normal mucosa tissue, colorectal adenoma tissue， and colorectal cancer tissue, and its relationship with tumorigenesis, tumor progression， and prognosis of patients with colorectal cancer . MethodsThe expression of CLIC1 protein was detected in 150 cases of colorectal normal mucosa tissues, 62 cases of colorectal adenoma tissues, and 187 cases of colorectal cancer tissues by using immunohistochemistry tissue microarray, and the relationships between the expression of CLIC1 protein and clinicopathologic features, and the survival rate of patients with colorectal cancer were analyzed. ResultsThe positive rate of CLIC1 protein expression in normal mucosa tissues (26.00%, 39/150), colorectal adenoma tissues (66.13%, 41/62), and colorectal cancer tissues (82.89%, 187/155) increased in turn and the difference was statistically significant (Plt;0.001). The expression of CLIC1 protein was related to TNM staging (P=0.007), but it was not related to gender (P=0.553), age (P=0.206), tumor diameter (P=0.185), tumor differentiation (P=0.062), and tumor location (P=0.598). The median survival time after surgery in patients with CLIC1 protein positive expression was 80 months, and it was 111 months in patients with CLIC1 protein negative expression. The survival rate of patients with CLIC1 protein positive expression was lower than that with CLIC1 protein negative expression by log-rank test (66.40% vs. 80.00%, P=0.031). ConclusionsThe expression of CLIC1 protein is related to the tumorigenesis and progression of colorectal cancer as well as the survival of patients with colorectal cancer. CLIC1 is a potential tumor biomarker.