Instrumental musicians may constitute the least recognized and most under-served large occupational group at high risk for upper-extremity musculoskeletal disorders (UEMSD). This study will investigate the cross-sectional prevalence and the one-year cumulative incidence and persistence of UEMSD, as defined by self-reported symptoms, within a population of professional musicians belonging to at least two and possibly three musician union(s), representing 1000-1500 members. Active musicians in each union will be asked to complete a mailed questionnaire on physical and psychosocial stressors in both primary (music) and secondary jobs, covering both generic ergonomic exposures and music-specific factors. Other items will include demographics, medical history and UEMSD symptoms. All participants in the first survey will be asked to complete a second questionnaire, one year later. We will estimate the frequency of specific exposures in music and other jobs as well as of UEMSD, and the separate and combined contributions of these exposures in the prevalence, cumulative incidence and persistence of UEMSD, including interactions between physical (biomechanical) and psychosocial factors and effect modification by exposures in secondary jobs. The effects of risk factors will be analyzed among professional musicians as a whole, by type of instrument, type of musical work, duration of years played, and hours per week practiced. The results of this study could be useful in preventing these disorders, by providing information for musicians, administrators of musician organizations/institutions (musician groups, symphonies, unions, conservatories), educators, instrument designers, and health professionals to use in 1. developing and modifying music training programs (i.e., establishing sequence or program of repertoire); 2. incorporating work organization factors in establishing job requirements and practice/work schedules; 3. redesigning instruments or designing external supportive devices or furniture/work space; and 4. enhancing efforts toward appropriate medical treatment and prevention education regarding musicians' UEMSD.