An apparatus for treating varicose veins includes a catheter (20) where the distal end is placed within a varicose vein and the proximal portion remains outside the body of the subject. A heating element (22) heats the vein. A cooling element (62) can be applied to an external surface of the skin above the vicinity of the heating element. A control unit (26) can drive the heating element to apply heat to the vein simultaneously. Alternatively, the control unit can apply a current to the heating element to resistively heat a resistive element. A method for treating a varicose vein includes inserting the elongated heating element into the vein, and driving the heating element to apply heat to the segment of vein simultaneously from the entire active heating portion.