This report of written testimony to the House of Representatives concerned the magnitude and scope of the problem of work related musculoskeletal disorders (MSDs) and two decades of experience and research amassed by NIOSH in this area of study. Musculoskeletal disorders have been among the most prevalent medical problems among workers in the United States, affecting 7% of the general population. The Bureau of Labor Statistics Annual Survey of Occupational Injuries and Illnesses indicated that in 1995, 62% of all illness cases were due to disorders associated with repeated trauma, excluding low back disorders. In 1994 approximately 32% or 705,800 cases were the result of overexertion or repetitive motion. Estimated annual costs of such injuries range from 13 to 20 billion dollars. Some examples were provided of research findings concerned with low back disorders, disorders of the neck and shoulders, and disorders of the hand, wrist and elbow. Information was provided concerning various factors such as the length and intensity of exposure and the significance of psychological factors. NIOSH has been using a public health approach to spread understanding and preventive methods so that the incidence and severity of work related musculoskeletal disorders will be reduced.