Abstract: An anti-theft device for an automotive vehicle such as a car or truck having fluid pressure-operated brakes is disclosed. The device includes a lockable member that, when activated while the brakes have been applied by the driver, inhibits any substantial change in the then existing fluid pressure condition in the brake fluid pressure system of the vehicle. The brakes thus remain locked, preventing normal movement of the vehicle, even if the brake pedal is subsequently released and the engine is running. The device can also include an additional lockable member for immobilizing the brake pedal to prevent its being depressed. Optionally, the device can also include one or more electrical switches which are operated, when either lockable member is activated, to ground out the distributor and/or open the ignition circuit at a point away from the ignition lock terminals, thereby to prevent starting of the engine. Preferably a special key is provided for releasing the lockable member, and special screws, e.g.