Case files or summary data, such as insurer claim reports, were examined for about 300 closed arbitration cases believed to represent the majority of cases closed nationally between 1970 and 1979. The large majority of cases were from the California Hospital and Medical Association's arbitration program. Not included are data from cases resolved in arbitration under prepaid group contracts. The arbitration data base yielded information separately by claim-producing incident, by claim, by defendant, or by forum. For comparative analyses, a litigation sample of 500 cases was obtained from the National Association of Insurance Commissioners' national survey, representing insured medical malpractice claims closed between 1975 and 1978. Major findings are that (1) arbitration appears to be the more efficient method, as measured in terms of time for report and processing; (2) the two forums appear to be equivalent with regard to frequency and amount of indemnity award; (3) there was no evidence that arbitration produces compromise or favors one side over the other; and (4) cases in arbitration were more likely to be ajudicated on the merits. Recommendations pertain to future research and immediate action. The appendixes contain an information manual for data in the medical malpractice data base, the the medical malpractice research data base (statement), a selected bibliography, and a methodological note on problems affecting forum comparison.