Objective. To estimate the incidence of musculoskeletal-related acute physical disability in the elderly (APDE). Methods. A primary care-based registry was established in Madrid's Health Area 7 from October 1, 2005 to September 31, 2006. We included all persons age >65 years, who were non-institutionalized and covered by the health cards assigned to the participating general practitioners (GPs). A case of APDE was defined as a moderate mobility alteration in the disability level within the Rosser's Classification System, in the last 3 months, related to a musculoskeletal cause. Incidence rates (IRs) were estimated per 10,000 person-years by direct standardization with a 95% confidence interval (95% CI). Results. Eight primary care centers and 23 GPs participated in the registry, covering 8,546 elderly patients. In the inclusion year, the GPs identified 147 new APDE cases in 106 patients. The annual estimated incidence of APDE was 331 cases per 10,000 person-years (95% CI 280 -389) and the IR of new patients with an APDE episode was 239 (95% CI 196 -288); the IR was higher in women (344 cases; 95% CI 279.8 -423.0) than in men (207 cases; 95% CI 127.0 -338.2). Conclusion. The incidence estimate of acute physical disability related to musculoskeletal disorders in the elderly should help us to determine the magnitude of this health problem, as well as the first step to establishing a specific practice for the recovery of cases and for the prevention of loss of functioning, mobility, and independence.