Cyclone Tracy devastated the city of Darwin during the night of December 24, 1974. By morning a city, of some 45,000 people and of 12,000 homes, had ceased to exist. The following is an account of how the health personnel in Darwin, both Government and private, dealt with this unique and overwhelming disaster. The situation can be considered to have been composed of six phases: Phase I, Preparation; II, The Cyclone; III, Casualties; IV, Emergency Centres - Air Evacuation; V, Health Clean Up; and VI, Reconstruction.