UNLABELLED Repetitive strain injuries are a common diagnostic label for musculoskeletal pain occurring at the workplace. Although many individuals present with diffuse pain, the diagnosis of fibromyalgia in this setting is rare. Our objective was to establish the point prevalence of the fibromyalgia syndrome in a population of assembly line workers in São Paulo, Brazil. METHODS Thirty-four workers with repetitive strain injury diagnoses were studied and compared with 49 workers, paired by age, sex, and labor function. All individuals were studied by a comprehensive clinical protocol. Diagnosis of fibromyalgia syndrome was established when the 1990 American College of Rheumatology criteria for this syndrome were met. RESULTS Among the 34 workers with the diagnosis of repetitive strain injuries, 58.8% fulfilled the American College of Rheumatology criteria for fibromyalgia syndrome, while only 10.4% of the controls met the same criteria. CONCLUSIONS Fibromyalgia syndrome was largely involved in the symptoms of patients with repetitive strain injuries, as opposed to coworkers with non-repetitive strain injuries. So, instead of the repetitive strain injuries label, many of these cases should be called fibromyalgic patients.