Abstract: Disclosed are cylinder lock arrangements which include a rotatable cylinder plug provided with recesses for guiding in axial direction blocking bars which cooperate with the cylinder housing to prevent in a blocking position thereof the rotation of the plug. The blocking bars are formed with blind bores which in a releasing axial position of the bars communicate with a key channel. The blind bores accommodate segmented pin tumblers which are controlled by control recesses on a lateral wall of a key so that upon the insertion of a correct key the separation planes of the segments of the pin tumblers coincide with the separation plane between the blocking bar and the clyinder plug. The key for the lock of this invention has a profile defined by alternating longitudinal ribs and longitudinal grooves whereby the crest regions of the ribs are formed with the control recesses arranged at different levels in accordance with the segments of the pin tumblers.