Identifying the medical treatment guidelines that determine the appropriateness of treatment for California workers1 compensation recipients. Provides an evaluation of medical guidelines that might be used to determine the appropriateness of treatment for work-related injuries in California. Of 72 guideline sets that were identified and screened, five comprehensive sets were found to satisfy the legislative requirements and state preferences. Based on results of a comparative evaluation of the technical quality and clinical content of the five guideline sets, recommendations are given for actions the state might take in the short term, intermediate term, and longer term.