This is a descriptive study of the medical responses to the bombings by terrorists in Madrid on 11 March 2004. The nature of the event, the human damage, and the responses are described. It describes the: (1) nature and operations associated with the alarm; (2) assignment of responding units and personnel; (3) establishment and operations of casualty collection points; (4) medical transport and distribution of injured victims; (5) prioritization and command; (6) hospital care; (7) psychosocial care; (8) identification of the dead; and (9) police investigation and actions. Each of these descriptions is discussed in terms of what currently is known and the implications for future planning, preparedness, and response.