Abstract: Unlocking of a vehicle door by insertion of implements other than the door key into the door is prevented by a guard housing within the door into which the key turnable inner end of the lock cylinder extends and which also encloses an otherwise vulnerable portion of the linkage which interconnects the lock cylinder and the door latching means. In a preferred form of the invention, the housing has an extension which extends below the lock cylinder and which is angled to extend to the outer shell of the door and then downward along the inner surface of the shell and which extends between the shell and the side impact beam of the door. The guard may secured in place by the same bolt that secures the handle assembly to the door and is wholly within and concealed by the door.