Method for detecting tampering of at least one compartment (4a, 4b, 4c, 4d, 4e) in a tank vehicle, the compartment comprising a bottom valve having a first sensor element associated therewith adapted to detect the opening/closing of the bottom valve and to generate a control signal indicative of the state of this bottom valve; and a product filling/discharge valve having a second sensor associated therewith adapted to detect the opening/closing of the filling/discharge valve and to generate a control signal indicative of the state of this filling/discharge valve; the compartment having a third sensor element associated therewith adapted to detect the presence/absence of product in the compartment and to generate a control signal indicative of the presence/absence of product in this compartment; the method comprising: - Setting a loading state of the compartment by a control unit from received control signals of sensor elements (10, 11, 12); - Setting the loading state as empty from received control signals indicative that the bottom valve is closed, the filling/discharge valve is closed and of the absence of product in the filling/discharge pipe; - Setting the loading state as loading from received control signals indicative that the bottom valve is open, the filling/discharge valve is open and of the presence of product in the compartment, starting from a compartment loading state as empty; - Setting the loading state as loaded from received control signals indicative that the bottom valve is closed, the filling/discharge valve is closed and of the presence of load in the compartment, starting from a compartment loading state as loading; wherein the tank vehicle comprises a box for housing the filling/discharge valves present in the tank vehicle and a fourth sensor adapted to detect the opening/closing of the box for housing the filling/discharge valves and to generate a control signal indicative of the state of this box for housing the filling/discharge valves; the method comprising, starting from a compartment loading state as loaded: - Receiving as a control signal generated by the fourth sensor element a signal indicative that the box for housing the filling/discharge valves is closed; - Setting the loading state of the compartment (4a, 4b, 4c, 4d, 4e) as sealed, from the received control signal. - Receiving by the control unit at least one control signal from any of the sensor elements (10, 11, 12, 16), indicative of a state change; - Detecting tampering of the tank vehicle compartment by the control unit, from the control signals received, if a control signal indicative of a state change of the element with which it is associated is generated by any of the sensor elements (10, 11, 12, 16) before the vehicle reaches a customer centre. - Setting a loading state of the compartment by a control unit from received control signals of sensor elements (10, 11, 12); - Setting the loading state as empty from received control signals indicative that the bottom valve is closed, the filling/discharge valve is closed and of the absence of product in the filling/discharge pipe; - Setting the loading state as loading from received control signals indicative that the bottom valve is open, the filling/discharge valve is open and of the presence of product in the compartment, starting from a compartment loading state as empty; - Setting the loading state as loaded from received control signals indicative that the bottom valve is closed, the filling/discharge valve is closed and of the presence of load in the compartment, starting from a compartment loading state as loading; - Receiving as a control signal generated by the fourth sensor element a signal indicative that the box for housing the filling/discharge valves is closed; - Setting the loading state of the compartment (4a, 4b, 4c, 4d, 4e) as sealed, from the received control signal. - Receiving by the control unit at least one control signal from any of the sensor elements (10, 11, 12, 16), indicative of a state change; - Detecting tampering of the tank vehicle compartment by the control unit, from the control signals received, if a control signal indicative of a state change of the element with which it is associated is generated by any of the sensor elements (10, 11, 12, 16) before the vehicle reaches a customer centre.