Background This study examined the relationship of repetitive work and other physical stressors to prevalence of upper limb discomfort, tendinitis, and carpal tunnel syndrome. Methods Three hundred ®fty-two workers from three companies participated. Job exposure levels for repetition and other physical stressors were quanti®ed using an observational rating technique. Ergonomic exposures were rated on a 10-point scale, where 0 corresponded to no stress and 10 corresponded to maximum stress. Job selection was based on repetition (three categories: high, medium, and low) to ensure a wide range of exposures. Physical evaluations on all participating workers were performed by medical professionals and included a self-administered questionnaire, physical exam, and limited electrodiagnostic testing. Results Repetitiveness of work was found to be signi®cantly associated with prevalence of reported discomfort in the wrist, hand, or ®ngers (odds ratio (OR) 1.17 per unit of repetition; OR 2.45 for high vs. low repetition), tendinitis in the distal upper extremity (OR 1.23 per unit of repetition; OR 3.23 for high vs. low repetition), and symptoms consistent with carpal tunnel syndrome (OR 1.16 per unit of repetition; OR 2.32 for high vs. low repetition). An association was also found between repetitiveness of work and carpal tunnel syndrome, indicated by the combination of positive electrodiagnostic results and symptoms consistent with carpal tunnel syndrome (OR 1.22 per unit of repetition; OR 3.11 for high vs. low repetition). Conclusions These ®ndings indicate that repetitive work is related to upper limb discomfort, tendinitis, and carpal tunnel syndrome in workers. Further research with a wider range of exposures is needed to evaluate the effects of other physical stresses alone and in combination.