Abstract: A lock for a door, window or similar is described, with a lock case (1) and a lock mechanism mounted in the lock case (1) with a bolt (3) which is mounted so as to be retractable and throwable and/or a spring-mounted retractable and throwable latchbolt (2). For improved protection against break-ins it is provided that the body of the bolt (3) has at least one external surface which extends along the direction of movement of the retracting and throwing motion and, along this direction of extension, has a constant surface profile which is formed to be uneven in the direction transverse to the direction of movement, with at least one peak and at least one trough. Particularly preferred are embodiments in which all external surfaces which extend in the direction of movement of the retracting and throwing motion have a wave structure.