Torsionally stabilized guide wire for use in larger vessels of the vascular system. A relatively flexible helical coil is positioned over the distal end portion of an elongated shaft which increases in flexibility toward its distal end. The coil is affixed to the shaft at the proximal and distal ends of the coil and at an intermediate point near the distal end. A jacket having an outer diameter substantially equal to the outer diameter of the coil covers the shaft between the proximal end of the shaft and the proximal end of the coil. In one disclosed embodiment, the jacket is formed by heat shrinking a tubular sleeve of polyethylene about the shaft.