This article describes and analyzes key aspects of the medical response to Hurricane Katrina in New Orleans. It is based on interviews with individuals involved in the response and on analysis of published reports and news articles. Findings include: (1) federal, state, and local disaster plans did not include provisions for keeping hospitals functioning during a large-scale emergency; (2) the National Disaster Medical System (NDMS) was ill-prepared for providing medical care to patients who needed it; (3) there was no coordinated system for recruiting, deploying, and managing volunteers; and (4) many Gulf Coast residents were separated from their medical records. The article makes recommendations for improvement.