【Abstract】 Objective To evaluate the role of ApoCIII in the diagnosis and differential diagnosis of UC．Methods Intestinal tissue samples were retrieved from 20032011 archived specimen at Department of Pathology, and assigned to UC group (n=38), CD group (n=29), ITB group (n=31), IL group (n=32), infectious enteritis group (n=32) and Behcet′s disease group(n=28). 10 cases were recruited as normal control group. The expression of ApoCⅢ in colonic mucosa were detected by immunohistochemistry. Positive cells were counted by Image Analysis．Results The expression rate of ApoCⅢ in intestinal mucosa of UC patients(4444±1071)was significantly higher than that of ITB(2076±477), CD (1880±360) , IL(1883±379) , Behcet's disease(1902±304), Infectious enteritis (2056±335) and normal control(3017±627)(p＜005). That of normal control(3017±627) was higher than ITB(2076±477) , CD(1880±360) , IL(1883±379) , Behcet's disease(1902±304) , Infectious enteritis(2056±335) ( p＜005). While there was no significant difference among the other five groups(p＞005).Conclusion ApoCⅢ is related with UC closely, and may play an important role in the pathogenesis, diagnosis and differential diagnosis of UC．