Disclosed is a deflectable tip guiding device, such as a catheter, that enables a physician, or other health care personnel, to vary the radius of curvature of the tip of the device. In one embodiment, a guiding device includes an elongate body and a deflectable distal tip. An elongate stiffener tube is coupled to the body for longitudinal movement relative thereto and has a distal end spaced a variable distance from the distal end of the tip, thereby serving as a fulcrum for the tip. Longitudinal movement of the stiffener tube relative to the body varies the distance between the distal ends of the tip and tube, which in turn causes a corresponding increase or decrease in the radius of curvature of the tip.