Cost data were retrieved from all claims of low back pain initiated during 1986 (N= 98 999) from computerized records of the Liberty Mutual Insurance Company. The mean cost per case was $6807; median cost, $391. Medical costs represented 31.5% of the total costs; indemnity costs, 67.2%. The total compensable cost for all low back pain in the United States was estimated to be $11.1 billion. Large variations were found to exist among different states in cost per case and percentage of costs for indemnity and medical payments.