To describe the implementation and the effects of a multifactorial fall prevention trial on the specified risk factors of falling, incidence of falls and injurious falls, and on specified secondary outcome measures; to describe the design of the study and to assess the success of randomization. Randomized-controlled trial. Recruitment started in March 2003 and lasted until the end of January 2005, when a total number of 591 participants was reached. Participants were randomized into two age groups (65-74 years and 75 years and over), then into an intensive multifactorial risk-based prevention programme or into a one-time counselling on fall prevention. The intervention included individual geriatric assessment, guidance and treatment, individual guidance on fall prevention, physical exercise in small groups, psychosocial group activities, lectures, home-exercises and home hazards assessment. A total of 293 people were randomized into the 1-year prevention programme and 298 into the control condition. The mean age was 73.5 years in both groups; 84% of the participants were women. The groups were well balanced at baseline in relation to risk factors of falls, and the only statistically significant difference was found in the amount of regularly taken medicines, which was significantly lower in the control group: mean 3.7 (SD 3.0) vs. 4.2 (SD 3.1), P=0.028. Participants were successfully randomized into a multifactorial fall prevention trial.