Kienbock's disease is an isolated disorder of the lunate bone resulting from vascular compromise to the bone. In stage IV, degenerative changes are present at the midcarpal joint, the radiocarpal joint, or both. The goal of proximal row carpectomy (PRC) is the creation of a new joint between the capitate and the radius. The aim of this prospective study was to evaluate the functional outcome after PRC in late stage Kienbock's disease. The evaluation included assessment of range of motion, grip strength, and pain reduction. Twelve wrists in 12 patients underwent proximal row carpectomy for the treatment of stage IV Kienbock's disease between 2002 and 2005. Objective and subjective function was assessed. The average length of follow-up was 2 years (range, 9 months to 4 years). There was one failure (8.3%) requiring fusion at three years. The eleven wrists that did not fail (91.7%) had an average flexion-extension are of 70 degrees, associated with an average grip strength of 80% of the contralateral side; all patients were very satisfied. The patients rated nine wrists as not painful, two as mildly painful, and one as moderately painful. Radiographs revealed reduced radiocapitate space in five and complete loss of the space in one. With the numbers available, there was no significant association between loss of joint space seen on radiographs and subjective and objective function. Overall, proximal row carpectomy had maintained a satisfactory range of motion, grip strength, and pain relief, and all twelve patients with Kienbock's disease, except one, were satisfied with the results and returned to their previous occupations. Caution should be exercised in performing the procedure in a young, heavy manual working patient.