Colorectal endoscopic submucosal dissection (ESD) is a technically demanding procedure with high risk of perforation, which has been reported about 5%. Risk factors for colorectal ESD perforation include inexperienced endoscopists, fibrosis, cecal location, large tumor size, etc. Thus, an organized training program is important for a trainee endoscopist to get the competency for safe colorectal ESD. Strategies for effective and safe colorectal ESD for lesions with fibrosis, cecal location, and large size are also necessary. Once perforation occurs, immediate clipping is the most important procedure for effective medical management. This lecture will cover the risk factors, diagnosis, and management of colorectal ESD.