Abstract: A plastic door lock comprises opposed flat inner and outer cover plates (1,1') each recessed to house slidable drag units (3,3'), and a core unit (2) located between the cover plates (1,1') housing a latch unit (4) which, on sliding movement of the drag units (3,3'), can be moved between a closed position and an open position. A limit switch (25) housed in the inner cover plate (1') can be pivoted between an unlocked position permitting movement of both the inner and outer drag units (3,3') to actuate the latch unit (4), and a locked position preventing movement of the outer drag unit (3) but being such that, on movement of the inner drag unit (3'), the limit switch (25) is returned to its unlocked position to enable actuation of the latch unit (4) from inside the door. The components of the lock are moulded from a plastics material.