Physical activity is usually considered as an important component of a healthy lifestyle, including a preventive effect on the risk of falls in the elderly. The relationship between physical activity and falls is complex: physical activity is a prerequisite to maintain neuromuscular functioning, necessary to keep balance and to react to a fall, but a higher level of physical activity also implies a greater exposure to environmental threats, possibly leading to a fall. Related to this greater exposure to threats, the use of a walking aid may protect against falls in those who have impaired mobility. In this cross-sectional study we investigated the relationship between daily physical activity and falls and the use of a walking aid in elderly subjects. Participants were 131 men and 563 women, aged 70 years and over (mean age and standard deviation: 82+/-6 years), living in homes for the elderly (n=335) and apartment houses for elderly (n=359). Data on baseline characteristics and falls in the previous year were obtained using a questionnaire. The level of daily physical activity in the previous year was obtained by means of a questionnaire regarding household and leisure activities. Subjects with a lower extremity fracture in the previous year were excluded from the analyses. Data were analysed using multiple logistic regression, adjusted for age, gender, and residence. In the past year, 40% of the participants fell at least one time, and 19% of the participants fell two times or more. Since falls and recurrent falls were nonlinearly related to the level of daily physical activity, the physical activity score was grouped into quartiles: the highest quartile corresponding to the highest activity level. Odds ratios (and 95% confidence intervals) for falls and recurrent falls for subjects in the highest quartile contrasted with those in the lowest quartile were 0.5 (0.3-0.9) and 0.3 (0.2-0.6), respectively. The risk of falls and recurrent falls was not lower for those with intermediate levels of daily physical activity. The use of a walking aid protected against falls in those with intermediate high activity levels (third quartile). It was suggested that the exposure to environmental hazards, due to some degree of physical activity may have been responsible for the nonlinear relationship between daily physical activity and falling. We conclude that a high activity level and the use of a walking aid may protect against falls.