Objective:To discuss the clinical significance of pathological diagnois in colorectal intraepithelial neoplasia and the principles of surgical treatment. Methods:Nintysix patients with colorectal tumors were treated in Shanghai the 8th People’s Hospital from January 2004 through December 2006.They was diagnosed as “intraepithelial neoplasia” by preoperative endoscopic biopsy.Among these cases,47 cases were diagnosed as low grade intraepithelial neoplasia,and 49 cases were high grade intraepithelial neoplasia.Two patients with adenoma were treated by polypectomy,22 patients treated by colectomy,43 patients treated by low anterior resection (LAR),8 patients treated by ia 38.29% were infiltrative carcinoma. Results:In 62 cases confirmed as adenocarcinoma,1 had liver metastasis,2 had involved adjacent tissues and 17 cases (64.58%) had reginonal lymph nodes metastasis. Conclusion:It should pay much attention to the pathological diagnosis in colorectal intraepithelial neoplastia, especially in the high grade intraepithelial neoplastia. If the location of the tumor was not involved to anal sphincter and in highly suspected case with malignant potiential,It prefer to treat with segmental resection of the bowel rather than local excision or polypectomy.