Ninety-one wrists in 82 consecutive patients with Quervain's disease were treated by the one surgeon between 1978 and 1987. The treatment of 79 wrists in 71 patients who had received their entire treatment from this surgeon is analyzed. Uniformity of injection technique is thus ensured. Initial treatment in 63 wrists was an injection of steroids and local anesthetic into the tendon sheath, which gave complete relief in 45 cases. Seven wrists received two injections before the pain abated. Only 11 of the 63 injected wrists had an operation. In 10 of these the extensor pollicis brevis tendon was in a separate compartment. It is concluded that injection of steroids is the preferred initial treatment in de Quervain's disease, giving complete and lasting relief in 80% of cases. If injection fails, it appears likely that the extensor pollicis brevis tendon lies in a separate compartment.