The flexor pollicis longus tendon is prone to attritive rupture and retraction. Direct repair is often not possible. Interposition grafting is a treatment option to restore tendon continuity, although the surgical technique and postoperative results have not been well defined. We report our experience with this procedure. 14 patients were prospectively followed for a minimum of 10 months after surgery. There was one postoperative failure of the tendon reconstruction. Postoperative strength was comparable to the contralateral side, but thumb range of motion was significantly reduced. In general, patients reported excellent postoperative hand function. This procedure seems a viable treatment option with lower donor site morbidity than tendon transfer surgery.