Purpose : To evaluate the necessity and effectiveness of a lunate excision in triscaphe fusion for the treatment of advanced Kienbock's disease. Materials and Methods : Twenty-six patients who underwent a triscaphe fusion for Kienbock's disease (IIIb) were analyzed. Fifteen patients received triscaphe fusion only and 11 patients received triscaphe fusion and a lunate excision. The indication for a lunate excision included pain and limited motion due to posterior impingement associated with a severely collapsed lunate. The range of motion and modified Mayo wrist score in the two groups were compared. The carpal height ratio, ulnocarpal distance ratio and radioscaphoid angle were measured on the plain radiographs, and the presence of degenerative change was evaluated. Results : The mean extension range was more preserved in the lunate excision group than in the lunate preserving group. Several radiology indices were similar in the two groups, but a degenerative change in the radioscaphoid joint was observed in 45.5% of the lunate excision group and in 13% of the lunate preserving group. Conclusion : When performing the triscaphe fusion in advanced Kienbock's disease, excision of the lunate can relieve the symptoms of posterior impingement. However, this procedure should be carried out carefully because degenerative changes in the radioscaphoid joint are frequently observed.