The OIG has examined CMS and Medicare contractor oversight of home health agencies (HHAs) in light of persistent concerns about Medicare fraud, waste, and abuse involving HHAs. In the report, “CMS and Contractor Oversight of Home Health Agencies,” the OIG concludes that the effectiveness of such oversight efforts is mixed. While two Medicare Administrative Contractors (MACs) reviewed by the OIG prevented a total of $275 million in improper payments and referred 14 instances of potential fraud in 2011, four Zone Program Integrity Contractors (ZPICs) did not identify any HHA vulnerabilities. The OIG also found limited instances of CMS inappropriately paying HHAs with suspended or revoked billing privileges. The OIG makes a series of recommendations in this area, including calling on CMS to establish additional contractor performance standards for high-risk providers in fraud-prone areas and to prevent inappropriate payments made to HHAs with suspended or revoked billing privileges. CMS concurred with the OIG recommendations.