The costs of public and private workers' compensation insurance were compared in this study. Information was obtained from the Social Security Administration. Exclusive state run workers' compensation insurance was identified in Nevada, North Dakota, Ohio, Washington, West Virginia, and Wyoming. Twelve other states had both private and public insurance, as well as self insured firms. The remaining 32 states had only private workers' compensation insurance. For the years 1980 to 1988, the average benefit to premium written ratio for all private workers' compensation insurers was 0.576, while that for the state run insurers was 0.736. For the years 1989 to 1993, the average benefit to premium ratios were 0.665 for private insurers and 0.757 for state run insurers. This disparity between public and private was still evident even after the taxes on the private firms were considered. The authors conclude that public workers' compensation insurance is more efficient and beneficial to the worker than private workers' compensation insurance.