<p>　The Iwate Doctor-Helicopter (IDH) service began in 2012 with Iwate Medical University Hospital as the base hospital. Iwate Prefecture covers a vast land area, second only to Hokkaido and comparable to Shikoku, and accounts for around 4% of the national land area. With a population density of 77.3 persons/km2, Iwate is one of the most sparsely populated areas in Japan. The density of doctors in the habitable area of Iwate is 0.67 doctors/km2, one-fifth the national average. The IDH service is thus indispensable for providing medical care in Iwate Prefecture. The topography of the prefecture causes many dead zones for mobile phone and radio reception, presenting an obstacle to communication and mutual location information sharing between the doctor helicopter and emergency services during responses. In April 2013, the three northern Tohoku prefectures of Aomori, Iwate, and Akita entered into an ‘Agreement on wide-area cooperation for the three northern Tohoku prefectures’ and have been working on ‘mutual accommodation of duplicate requests in cases of bad weather or when the helicopter of one prefecture is already responding to a different case’. This agreement allows for the dispatch of helicopters from other prefectures in cases where the helicopter from the home prefecture cannot be dispatched due to overlapping requests or bad weather, when there are too many injured or sick patients for the home helicopter to respond to alone, or when the doctor onboard the helicopter from the home prefecture judges that dispatch of a different helicopter would be more effective. Recently, for the sake of residents living on prefectural and metropolitan borders, wide-area coordination of doctor helicopters has been urged in order to allow for prioritization of dispatch according to ‘living area’ based on distance as an indicator. However, when dispatch requests are made using distance as an indicator, it is necessary to fully consider whether there are problems faced by each individual region that cannot be inferred from distance alone. We retrospectively investigated the actual circumstances surrounding dispatches from Iwate Prefecture to the Ninohe and Kuji regions bordering Aomori and Akita Prefectures, extracted the current issues in our own prefecture, and examined what should be done to implement and promote smooth, wide-area medical cooperation. The difference between IDH service and ambulance rendezvous point (RP) arrival times was -7.51 ± 14.26 minutes in the Ninohe region and -1.34 ± 13.43 minutes in the Morioka region, where IDH RP landings were earlier than ambulance RP arrivals. In Kuji region, the ambulance RP arrival time was 1.69 ± 9.04 minutes, which was earlier than the IDH RP landing. However, with regard to the time spent on stand-by at the RP following arrival, this was 7.39 ± 12.41 minutes in the Kuji region, which was significantly shorter than the 8.43 ± 15.77 minutes in the Morioka region. In all regions, there were instances of delayed IDH RP landings due to late arrival of the ground support team at the RP. Therefore, a key element for the smooth execution of IDH operations is the RP arrival time of the emergency and ground support teams. Close exchange and review of information on the mission in question between the communications specialist and fire department is important, and the doctor in charge needs to take appropriate medical control from an early stage based on the results of such discussion. The results of this survey can be used in other regions, and the issues in each region should be discussed again during the post-event verification with each cooperating organization.</p>