Previous controlled studies have shown that preventive home visits are a promising method for disability prevention in elderly persons; however, due to the lack of data on cost effectiveness and optimal intervention methods, there is still debate on their usefulness. Therefore, additional controlled studies must use new methods to resolve these unanswered issues. We present a novel approach used in the project EIGER (Evaluation of In-Home Geriatric Health Visits in Elderly Residents), an ongoing randomized controlled trial of preventive home visits in community-residing persons aged 75 years and older in Bern, Switzerland. The intervention consists of in-home visits with structured comprehensive geriatric assessment and follow-up by specially trained nurses who collaborate with geriatricians and an interdisciplinary team. Special methods were used to optimize the sample size, to improve the health care cost analysis, to minimize and explore refusal to participate, to apply stratified randomization for subgroup analysis, and to evaluate the intervention process with a tracer method. Selected baseline findings (N = 791, mean age 82 years, 73% female) include uncontrolled systolic hypertension (54%), balance/gait disorder (9%), cognitive impairment (7%), 6 or more medications (21%), depressive symptoms (10%), and impaired basic ADL (15%). Baseline findings demonstrate that this study is likely to contribute to some of the unresolved issues of in-home prevention for older persons.