The Tokyo subway sarin attack was the second documented incident of nerve gas poisoning in Japan. The authors report how St. Luke's Hospital dealt with this disaster from the viewpoint of disaster management. Recommendations derived from the experience include the following: Each hospital in Japan should prepare an emergent decontamination area and have available chemical-resistant suits and masks. Ventilation in the ED and main treatment areas should be well planned at the time a hospital is designed. Hospital disaster planning must include guidance in mass casualties, an emergency staff call-up system, and an efficient emergency medical chart system. Hospitals should establish an information network during routine practice so that it can be called upon at the time of a disaster. The long-term effects of sarin should be monitored, with such investigation ideally organized and integrated by the Japanese government.