The methods and clinical outcomes of intrasheath triamcinolone injection in the treatment of de Quervain's disease are described. We used 38 hands of 36 patients. A mixture of 1 ml of triamcinolone and 1 ml of 1% lidocaine hydrochloride was injected, with an interval of 2 weeks. The fluid was injected into one point above the induration for the first 18 hands and into two points over the extensor pollicis brevis and abductor pollicis longus tendon in the induration for hands 19-38. The efficacy rate was 89%, with the treatment results of the two-point injection better than those of the one-point injection. Recurrence was observed in ten hands, and complications in 13 hands; however, over 90% of patients were satisfied with the injection. The accurate injection of triamcinolone into the sheath of both the extensor pollicis brevis and abductor pollicis longus tendon was considered very effective for de Quervain's disease.