Abstract: A roller blind for closing openings in buildings, such as windows, doors, or the like, which blind is formed from a plurality of laminated strips which are attached one to the other and whose ends are guided in guide rails, and has an insertable bolt for locking the roller blind and which is provided in the lowermost laminated strip. This lowermost strip is formed as an end bar housing said bolt which can penetrate into an opening in one of the guide rails in the closed (locked) position under the action of a spring. For unlocking purposes, a cord which is secured to the bolt, is guided upwards through endpieces of the laminated strips and secured so that, upon winding the laminated strips around the winding shaft, the bolt is withdrawn from the opening in the guide rail against the action of the spring.