Abstract: A cylinder lock has a lock body with a cylindrical throughbore and two longitudinally extending grooves in its internal surface. A lock cylinder is mounted in the throughbore for rotation therein between a locking position and an unlocking position and has a longitudinally extending key passage and is responsive to the insertion of a suitable magnetic key in the key passage to enable rotation thereby from a locking to an unlocking position. A plurality of magnetic bodies are mounted on both sides of the key passage for rotation about an axis perpendicular to the longitudinal axis of the cylinder to a unique angular position when the suitable key is inserted with corresponding recesses which are longitudinally aligned in two lines when the magnetic bodies are in their unique position.