At the request of Senator William Roth, Jr., the General Accounting Office (GAO) reviewed Medicare and Medicaid fraud investigations that agency inspectors general referred to the Department of Justice for prosecution to identify characteristics of alleged fraud against the government and to determine actions taken against those caught defrauding the government. A review of 279 Medicare and Medicaid cases from the Office of Inspector General revealed that 89% of the cases involved submission of false claims; 3% involved kickbacks; and 2% involved perjury, theft, or misuse of government property. About 85% of cases involved health care providers, of which approximately 50% were medical doctors. About 50% of cases involved allegations of fraud committed against the Medicare program, 30% involved Medicaid, and 9% involved more than one health care program. Three types of action which can be taken against health care providers who commit Medicare or Medicaid fraud were identified: (1) subjection to criminal or civil action by the Department of Justice; (2) assessment with a civil monetary penalty; and (3) suspension from participating in the Medicare and Medicaid programs. A review of 351 cases revealed that, in 275 cases, subjects were either prosecuted, fined, or suspended from participation in the program. New procedures are being initiated by the Office of Inspector General to ensure that vulnerabilities in the Medicare and Medicaid programs are communicated to health care program managers so that underlying causes of fraud can be corrected. The GAO will review this system in the future. (NB)