Summary: This report updates the status of corrective measures taken by federal agencies to address internal control weaknesses that could affect the United States' ability to effectively respond to chemical or biological terrorist attacks. GAO, which cited these weaknesses in 1999, found that the agencies have significantly improved accountability over the medical supplies needed to treat victims of chemical or biological terrorism. However, ensuring that supplies are current, accounted for, and readily available depends in large part on successful collaboration with other entities. Until the Centers for Disease Control and Prevention (CDC) and the Office for Emergency Preparedness (OEP) formalize ad hoc arrangements with other entities covering the storage, management, stock rotation, and transporting of supplies, they run the risk that, in the event of a chemical or biological attack, the appropriate supplies will be unavailable. Also, unless the agencies' inventory requirements lists are up-to-date and reflect their own identified needs, the agencies cannot guarantee that they have the supplies on hand to fulfill their mission.