In this paper, we propose a location model for helicopter emergency medical service systems. When a critical accident occurs, EMS-Helicopters are used to carry emergency patients to a hospital as soon as possible. In this situation, the helicopters require heliports to pick up patients. Therefore, the locations of helicopter stations and heliports are important factors to ensure the effective operation of the system. We formulate the proposed problem as an integer programming problem which seeks to find locations of both stations and heliports to maximize the total demand points which can arrive at a hospital within a given time. We apply our method to an assumed square city in which demand points are uniformly distributed, and consider the influences of the locations of stations and heliports on the level of service provided.