This was a prospective epidemiological study of musculoskeletal symptoms and musculoskeletal disorders among newly hired video display terminal (computer) users in the metropolitan Atlanta area. Information collected from study participants included demographic characteristics, personal health information, daily number of hours worked in the office, the number of hours spent typing, and other exposure information. Information about symptoms was collected weekly. An ergonomist visited all study participants and collected standard information about workstation configuration and postures assumed by study participants while typing. Study participants were asked to complete a questionnaire about occupational psychosocial stress. Study participants who reported discomfort meeting study criteria were offered a standard physical examination by a specially trained certified hand therapist. Incident symptoms and incident disorders were recorded separately for the neck and shoulder (neck/shoulder) and the hand and arm (hand/arm). Analyses were conducted separately for the four health outcomes, neck/shoulder symptoms, neck/shoulder disorders, hand/arm symptoms, and hand/arm disorders. The results of this prospective epidemiological investigation provide important new information about 1) ergonomic exposures sustained by those using video display terminals, 2) the prevalence and incidence of specific upper extremity musculoskeletal disorders among video display terminal users over a three year period, and 3) the relationship between ergonomic exposures and musculoskeletal disorders free from methodological problems encountered with more common study designs. Control of posture among computers cannot be accomplished by manipulation of workstation dimensions alone. This finding is useful to ergonomists, engineers and furniture designers who want to encourage specific postures among computer users. The greater correlations between elbow height and keyboard height than between eye height and monitor height suggests that greater attention needs to be given to adjustability of monitor height. This finding is useful to ergonomists, engineers, and furniture designers who want 0 design office equipment and furniture that allows for the same degree of control of neck posture as upper limb posture. Musculoskeletal disorders can be expected to occur commonly (i.e., more than half of users) among computer users. This finding is useful to physicians, employers, workers, ergonomists, and policy makers interested in assessing the magnitude of the problem of musculoskeletal disorders among computer users. Neck/shoulder ailments are more common than hand/arm ailments among computer users. This finding is useful to physicians and therapists who provide care to those who use computers. The most common neck/shoulder disorder was tension neck syndrome (somatic neck pain disorder) and the most common hand/arm disorder was deQuervain's tendonitis. This finding is useful to physicians and therapists who provide care to those who use computers. The identification of ergonomic risk factors among computer users is useful to ergonomists, physicians, employers, insurers, regulators, and employees interested in reducing the risk of musculoskeletal disorders among computer users. The finding that hours per week of keying is a significant predictor of hand/arm symptoms and hand arm disorders is useful to ergonomists, physicians, employers, insurers, regulators, and employees interested in reducing the risk of musculoskeletal disorders among computer users.