The increasing trends of cumulative trauma disorders of the upper extremities (CTDUEs) in US industry is well established; however, systematic examination of potential reasons for these trends has been lacking. Data from the United States Bureau of Labor Statistics and from Liberty Mutual Group workers' compensation claims were used to count CTDUEs. The proportions of all Bureau of Labor Statistics' cases and Liberty Mutual Group workers' compensation claims that resulted from CTDUEs were estimated for the years 1986 to 1993. The proportions by occupation (job classification code), gender, potential video display unit use, and in the meat-packing industry are described. Both data systems show a steady increase in cases and claims from less than 1% in 1986 to about 4% in 1993. Women and specific occupational categories are over-represented with respect to CTDUEs. A shift to service industry work and video display unit use do not appear to be strongly related to the increased reporting of CTDUEs, whereas increased productivity, an increased number of women in the work force and general awareness of CTDUEs in the media and health care system may be related. Coding and definition problems still limit these conclusions, however.