Abstract: Objective: To explore the role of HAI-1 in colorectal cancer and to provide evidence for roles thatHAI-1 plays in tumor development and progression. Methods: The expression of HAI-1 was detected by immunohisto-chemistry in normal and cancerous tissues of the digestive tract, breast and lung. A total of 52 paraffin-embedded col-orectal cancer specimens were detected for association between HAI-1 expression and clinicopathologic features. Results: The expression of HAI-1 was found in various normal epithelial tissues and/or corresponding cancer tissues. In 38 casesof colorectal cancer with paired specimens from cancer, adjacent normal mucosa and glandular epithelium, elevated ex-pression of HAI-1 was detected in normal mucosa and cancer tissues whereas lower expression of HAI-1 was detected inglandular epithelium (P<0.001). In the 52 colorectal cancer tissues, the immunoreactivity of HAI-1 protein showed a sig-nificant correlation with histological differentiation, and HAI-1 expression was significantly lower in poorly differentiatedcolorectal cancer tissues than in well and moderately differentiated colorectal caners(P<0.05). Age, gender, tumor location,lymph node metastasis, and cancer stages were not found as correlation factors (P>0.05). Conclusion: Aberrant expressionof HAI-1 is a common feature of carcinogenesis and may contribute to the occurrence, progression and differentiation ofcolorectal cancer. It may also serve as a marker for colorectal epithelial differentiation.