Falls among the elderly, although associated with substantial morbidity and mortality, have not been previously the subject of a longitudinal study. This five-year prospective study of an active ambulatory institutionalized population over 65 years of age, revealed an annual fall rate of 668 incidents per 1000, with a rising frequency in successive age groups after age 75. Forty-five per cent of all subjects suffered at least one fall during the study period. Women had a higher fall rate in all age groups and the severity of their injuries appeared to increase with age. Injuries severe enough to be brought ordinarily to the immediate attention of a physician occurred in 17.5% of falls. Among subjects who ultimately died after suffering many falls, there appeared in some to be a 'clustering' of falls prior to death.