Abstract: The invention relates to making a questionnaire-based survey in a cellular radio system including a central device and a number of independent terminal devices, where between the terminal devices and the central device, data transmission connections can be made. In the method, the central device receives an inquiry message and/or an inquiry table from the terminal device of the researcher, said message defining the survey group that the inquiry message relates to. The central device investigates which predetermined terminal device group and/or inquiry table stored in the central device the received inquiry message relates to, and transmits a notice of the received inquiry message, or at least part of the received inquiry message, and/or a questionnaire to those terminal devices that belong in the terminal device group that the received inquiry message relates to.