Method of manufacturing a differentially heat treated catheter guide wire

A method of making a catheter guide wire for guiding a catheter, said method comprising:

• forming a wire member comprising a superelastic Ni-Ti alloy wire as a base material, said base material having a proximal end portion and a leading end side;
• dividing said leading end side of said base material into a plurality of areas along the length thereof and a distal end portion, said plurality of areas comprising an intermediate portion between said proximal and distal end portions;
• and
• subjecting only said intermediate portion and said distal end portion to a primary heat treatment at a temperature of 400.degree. to 500.degree. C. for about two hours, and then subjecting only said distal end portion to a secondary heat treatment at a temperature of about 200.degree. C. for about 24 hours, whereby said proximal end portion is not heat treated after cold rolling, such that said distal end portion, after said primary and secondary heat treatments, has a yield stress of approximately 5 to 7 kg/mm.sup.2, and at least one of said areas at said intermediate portion, after said heat treatment, has a yield stress of approximately 11 to 12 kg/mm.sup.2.