The computer mouse is now present in virtually every office environment because of the recent adoption of the graphical user interface. However, Karlqvist et al. (1994) pointed out that there still remains a paucity of work on the musculoskeletal problems associated specifically with computer mouse use. Likewise, there have been no published data on the magnitude of upper extremity musculoskeletal disorders associated with computer mouse use. In order to ascertain this magnitude, claims data from the Liberty Mutual Group were reviewed for the years 1986 to 1993, inclusive. Count, total cost and average cost per claim for all claims associated with computer use and computer mouse use were determined for the years in question. It was concluded that although there are few claims related to computer mouse use, it appears to be a growing problem, and therefore, perhaps, deserves more research and intervention attention. However, the present magnitude is less than for other musculoskeletal disorders.