Abstract: An anti-theft device for a motor vehicle includes a starter-connected ignition switch which has a first accessible terminal, and a second substantially non-accessible terminal connected to a third substantially non-accessible terminal of a voltage dropping means, such as a resistor. A relay has a coil and at least a pair contacts closable by operating the ignition switch, and is connected in series with a circuit breaker, the voltage dropping means, the ignition switch and a voltage source. The circuit breaker trips at a predetermined current setting, and the coil is designed to burn out at a current just exceeding the predetermined current. Periodically openable contact-means actuate the motor vehicle's engine and are energizable by the pair of contacts. The circuit breaker trips upon a thief shorting the accessible terminals, and the relay coil burns out upon the thief shorting the circuit breaker.