A method for locating mobile terminals is provided. First, information of a home Public Land Mobile Network (PLMN) of a target mobile terminal, the location of which is to be determined, is checked in response to a location service request from a client. Then, information of a visited PLMN, where the target mobile terminal is currently located, is checked based on the checked information of the home PLMN. The home PLMN calculates location assistance information of the visited PLMN using specific location information of the visited PLMN. The location assistance information is transferred to the target mobile terminal. This allows location information of a mobile terminal to be obtained irrespective of the area or communication network where the mobile terminal is located. It is thus possible to locate a mobile terminal in an area where no location assistance information is provided.