Objective: To explore associations between physical activity and the risk of falls and fractured bones in community-dwelling older women. Design, setting and participants: A prospective observational survey with three and six-year follow-ups. The sample included 8188 healthy, community-dwelling women, aged 70-75 years in 1996, who completed surveys as participants in the Australian Longitudinal Study on Women's Health. Women who reported a recent serious injury from falling were excluded. Outcomes were reports of a fall to the ground, injury from a fall, and a fractured bone in 1999 and 2002. The main predictor variable was physical activity level in 1996, categorised on the basis of weekly frequency as none/very low, low, moderate, high and very high. Covariates were demographic and health-related variables. Logistic regression models were computed separately for each outcome in 1999 and 2002. Main results: In multivariable models, very high physical activity was associated with a decreased risk of reporting a fall in 1999 (odds ratio (OR) 0.67; 95% Cl 0.47 to 0.95) and in 2002 (OR 0.64; 95% Cl 0.43 to 0.96). High/very high physical activity was associated with a decreased risk of a fractured bone in 2002 (OR 0.53; 95% Cl 0.34 to 0.83). No significant association was found between physical activity and injury from a fall. Conclusions: The results suggest that at least daily moderate to vigorous-intensity physical activity is required for the primary prevention of falls to the ground and fractured bones in women aged 70-75 years.