BACKGROUND AND AIMS: Preventive home visits were introduced by legislation in Denmark in 1998. This ongoing randomized controlled intervention study introduces a model where preventive home visits to elderly people are carried out in a standardized way, focusing on early signs of disability and on physical activity. The study includes general practitioners (GPs) in relevant parts of the assessment and endeavors coordinated interdisciplinary follow-up. Our main aim was to investigate whether this model gives enhanced active life expectancy, but the focus of the present paper is the design of the study. METHODS: The design was a prospective, controlled, follow-up study conducted over a 3-year period (1999-2001) with randomization and intervention at the community level, and outcomes measured at an individual level among people living in those communities. The study included 17 pairs of intervention and control communities (34 in total), including 2104 persons aged 75-80 years in the intervention communities (participation rate, 70.8%) and 1956 persons in the control communities (p.r. 70.3%). The main outcome measure is change in functional ability after 1.5 and 3 years. Other outcomes are mortality, and hospital and nursing home admissions. Intervention communities received systematic education and written materials; two key representatives from each community also attended bi-annual follow-up meetings. Control communities did not receive any intervention but were allowed to conduct a preventive program completely on their own. RESULTS: Baseline characteristics were similar in the intervention and control communities with regard to size, rural and urban characteristics and geriatric services, and the individual characteristics of participating persons living in these communities were also comparable. The intervention was well accepted and feasible. CONCLUSIONS: When results become available, the study should reveal the most important factors for preventive home visits to elderly people.