Disclosed is an ablation method and apparatus used to close veins for treatment of venous insufficiency disease. The apparatus includes a catheter proportioned for insertion into a vein, a pair of inflatable balloons spaced apart on the catheter body, and an ablation electrode array disposed between the balloons. According to the disclosed method, the catheter is introduced into the vein to be treated and the balloons are distended. Blood is flushed and aspirated from the site between the balloons. RF power is applied to the electrode array, causing scarring of the vessel walls and eventual sealing of the vein.