The large number casualties caused by the 1995 Great Hanshin and Awaji Earthquake created a massive demand for medical care. However, as area hospitals also were damaged by the earthquake, they were unable to perform their usual functions. Therefore, the care capacity was reduced greatly. Thus, the needs to: (1) transport a large number of injured and ill people out of the disaster-affected area; and (2) dispatch medical teams to perform such wide-area transfers were clear. The need for trained medical teams to provide medical assistance also was made clear after the Niigata-ken Chuetsu Earthquake in 2004. Therefore, the Japanese government decided to establish Disaster Medical Assistance Teams (DMATs), as “mobile, trained medical teams that rapidly can be deployed during the acute phase of a sudden-onset disaster”. Disaster Medical Assistance Teams have been established in much of Japan. The provision of emergency relief and medical care and the enhancement and promotion of DMATs for wide-area deployments during disasters were incorporated formally in the Basic Plan for Disaster Prevention in its July 2005 amendment.

The essential points pertaining to DMATs were summarized as a set of guidelines for DMAT deployment. These were based on the results of research funded by a Health and Labour Sciences research grant from the, Labour and Welfare (MHLW) of the Ministry of Health. The guidelines define the basic procedures for DMAT activities—for example: (1) the activities are to be based on agreements concluded between prefectures and medical institutions during non-emergency times; and (2) deployment is based on requests from disaster-affected prefectures and the basic roles of prefectures and the MHLW. The guidelines also detail DMAT activities at the disaster scene of the, support from medical institutions, and transportation assistance including “wide-area” medical transport activities, such as medical treatment in staging care units and the implementation of medical treatment onboard aircraft.

Japan's DMATs are small-scale units that are designed to be suitable for responding to the demands of acute emergencies. Further issues to be examined in relation to DMATs include expanding their application to all prefectures, and systems to facilitate continuous education and training.