Abstract: Opioid-induced constipation (OIC) is the most common side effect of opioid. OIC influences the quality of life of pa-tients suffering from cancer pain. However, given that the drug is often overlooked and underappreciated, most of the time, the patients would avoid or abandon using opioid and, as a result, they continuously suffer from cancer pain. Therefore, OIC prevention and man-agement must be made before opioid use. The consensus on the diagnosis of OIC has only been reached recently. Thus, a unified defini -tion of OIC must be developed to exchange therapeutic option among departments in hospitals and compare treatment outcome. The di -agnosis of OIC is discussed, and the management of OIC, including medicinal and non- medicinal treatment, is summarized. Mean -while, the initial program for prevention and treatment of OIC is established to make OIC management more convenient for clinical physicians. Much work is still needed to establish a consensus on OIC diagnosis and a suitable program for prevention and treatment of OIC.