Two forms of treatment of Kienböck's disease were compared in a total of thirty-seven wrists. Sixteen had been treated conservatively and were followed-up for an average of twenty years. Twenty-one had undergone silicone replacement arthroplasty an average of five years prior to review. Clinical results of conservative treatment showed four (25%) good, six (37.5%) fair and six (37.5%) with a poor result. Radiological deterioration was seen in only a quarter of cases. After silicone replacement there were nine (43%) good and seven (33%) fair. Five (24%) cases had a very poor result associated with dislocation of the prosthesis but design improvements have made this less frequent. Radiological abnormalities were noted in more than half of cases treated by silicone replacement arthroplasty. These included carpal collapse, scapho-lunate diastasis and generalised degenerative changes in the carpus. There were two cases with cyst formation in the capitate which closely resembled previous reports of silicone synovitis.