Purpose: In Japan, only a few studies reported self-management systems of narcotic drugs among hospitalized patients. Our purpose was to develop a self-management system for patients and assess its effectiveness. Methods: Based on the results of a questionnaire administered to our hospital medical staff, methods of selecting eligible patients and methods of self-management of narcotic drugs were determined by a multi-professional team. Selection criteria for eligible patients were: 1) satisfactory results on assessment of the patient's ability to self-manage orally-administered drugs; 2) satisfactory results on assessment of the patient's ability to self-manage narcotic drugs; 3) physician's consent was obtained; and 4) the patient wanted to participate in this program. After the period of self-management of drug administration, questionnaires were distributed to the patients and medical staff in the general ward. Results: One hundred hospitalized patients used narcotic drugs between April 2008 and March 2009. Among them, 26 patients met the criteria for self-management of narcotic drugs, and 20 voluntarily participated in the program. There were no reports of missing or stolen drugs. There were no reports of administration of incorrect dose of the drug during the self-management period (average 15.0 days). Ninety-four percent of the self-managing patients provided positive feedback about self-management of narcotic drugs, such as mental stability by having drugs on hand and no problems in self-management. Seventy-five percent of staff members answered that the self-management system of narcotic drugs should be continued. Conclusion: Our results suggest that this system of narcotic drug self-management is safe and appropriate. Palliat Care Res 2010; 5(1): 114-126