Colitis cystica profunda is a rare benign condition characterized by the presence of mucus-filled cysts in the submucosa of the colon and the rectum. Although it may diffusely involve the entire colon, this disease primarily affects the pelvic colon and rectum. It has rarely been described in the pediatric literature. The surgical treatment has been widely advocated. We report a 7-month-old case, successfully treated by colonoscopic polypectomy without complication. Histologically, components of juvenile retention polyp were mixed with colitis cytsica profunda.