Abstract: A balloon catheter (1) comprising a device (3) located adjacent the distal end (12) of a catheter (10) of the balloon catheter (1) for guiding a boring tool (6) or other instrument into an occlusion (6) in a vessel (8) comprises a guide element (30) located adjacent a distal end (12) of the catheter (10). A penetrating element (33) defining a first guide bore (38) extending therethrough and terminating in a distal cutting edge (40) is rotatable in a second guide bore (45) extending through the guide element (30) located adjacent the distal end (12) of the catheter (10). External threads (49) on the penetrating element (33) are engageable with internal threads (50) located in the second guide bore (45) of the guide element (30), so that by rotating the penetrating element (33) with an operating member (52) the distal cutting edge (40) of the penetrating element (33) is urged outwardly of the second guide bore (45) and into cutting engagement with the occlusion (6) in order to penetrate the occlusion (6).