BACKGROUND: Patients with a long history of ulcerative colitis (UC) are at risk of developing a serious complication known as UC-associated neoplasia (UCAN). Because the treatment strategy for UCAN greatly differs from that for sporadic tumors, UCAN needs to be distinguished from sporadic tumors. This article provides an overview of the current status and future challenges regarding the surveillance colonoscopy (SC) and endoscopic submucosal dissection (ESD) of neoplastic lesions in patients with UC. SUMMARY: To reduce the risk of associated mortality, the current guidelines recommend initiating SC using chromoendoscopy with high-definition colonoscopy 8-10 years after the confirmation of a UC diagnosis. However, the endoscopic diagnosis of UCAN is occasionally challenging and requires a stepwise approach using multiple endoscopic modalities. The worldwide consensus is that a diagnosis of high-grade dysplasia or higher is an indication for proctocolectomy. Although the management of low-grade dysplasia (LGD) remains controversial, the SCENIC consensus statement recommends the complete removal of "endoscopically resectable" LGD, followed by monitoring. ESD was developed in Japan, allows for the removal of complex gastrointestinal lesions, facilitates the treatment of LGD, and enables precise pathological evaluations to differentiate between UCAN and sporadic tumors and to determine the grade of dysplasia in UCAN. Close endoscopic surveillance should follow complete endoscopic resection. A Japanese expert consensus meeting recommended the performance of follow-up SC 6-12 months after complete resection with ESD. KEY MESSAGES: The roles of ESD for UCAN are to treat LGD and to enable the histopathological examination of complete excisional biopsy specimens to differentiate between UCAN and sporadic tumors and grade the dysplasia of UCAN. In future, prospective cohort studies are needed to better assess the clinical outcomes of ESD in patients with UC.