Abstract: A system for preventing fraud when using a taximeter that utilizes a stage for detecting a load condition in a taxi and for recording signals corresponding to the load and driving condition of the taxi and to whether the taximeter is switched on or off. The load detection stage is adapted to detect the load on at least the rear wheels (2b) of the taxi (1), and to detect a change from a zero point indicating the unloaded condition. Another stage detects the fuel consumption and emits a signal for adjusting, at least at intervals, the load zero point in correspondence with this consumption. The load detection stage (13) is adapted to emit an alarm signal when the detected load change exceeds a given threshold value while the taximeter (4) is switched on.