In such an aging society as Japan, with decreasing number of children. Social activity of senior citizens is important for the well-being and the activation of whole societies. Promoting volunteer activities of senior citizens may serve as one useful plan; however, few researchers have examined the impact of volunteer work on the physical and mental health of senior citizens in Japan. In this study, a survey of previous studies that appeared after 1970 in North America, several findings were obtained: (1) Volunteering among senior citizens improves their mental well-being; (2) Few previous studies reported volunteering improves physical health such as protection for mortality and incidence of disability, compared to mental well-being; (3) Effects of volunteering might depend on gender, race, health status, socioeconomic conditions, and social networks of senior citizens--more impact can be expected on physical health of persons of advanced age; (4) Few previous studies focused on interactions of contents of volunteering programs; (5) Although several studies have reported that 40-100 volunteering hours per year were best quantitative level for health, this remains equivocal; (6) The conventional hypothesis that volunteering, through improvement in psychological, physical, and social factors, may improve ones health, needs assessment in terms of actual impact. Moreover, mechanisms of any influence remain to be clarified. From the point of practical use of volunteering as a health promotion program, it is necessary to explore better content and time engaged, as well as the numbers of groups to which senior citizens belong. Long-term longitudinal and intervention studies are desirable in this area in Japan, focusing on older candidates who are still healthy.