Abstract: A cylinder lock, especially for motor vehicles, comprising a housing (1) in the inner cylindrical cavity of which there is arranged a cylinder core (2) that is equipped with a key channel (22) and spring-loaded tumblers (20, 20?), wherein, when no appropriate key is fully inserted into the key channel (22), blocking projections (201) of the tumblers (20, 20?) protrude into a blocking groove (13, 13?) formed in a member in which the cylindrical core (2) is supported for turning and, when the appropriate key is fully inserted, the blocking projections (201) of the tumblers (20, 20?) do not extend beyond the periphery of the cylindrical core, wherein the cylinder lock is further provided with means for coupling the cylindrical core (2) with an output member (3) of the cylinder lock when the cylindrical core is being turned by the appropriate key, and for uncoupling of the cylindrical core (2) from the output member (3) of the cylinder lock when the cylinder core is turned by means of a false key or forcibly, the