We evaluated the functional outcome 3 (2-12) years after arthroplasty in 29 proximal humerus fractures. The patients' average age at the time of surgery was 71 (47-87) years. The follow-up included a full clinical examination by an independent observer, a questionnaire concerning activities of daily living and pain, and radiographs. The shoulders had a marked reduction of performance, with a Constant score mean of 38 (16-69). All patients were able to eat with utensils, 10 could comb their hair, 19 managed to wash the contralateral armpit, 3 could reach the back pocket and 12 were able to take care of the perineal area. On the VAS-scale (0-100 mm), pain at rest was mean 21 (0-53) mm and on motion 47 (0-91) mm. The patients were stratified regarding surgical treatment within 3 weeks (18 acute vs. 11 late) and prosthetic design (14 Neer II vs. 14 Global modular) without significant differences, as assessed by the Constant scores. We conclude that the treatment of severe proximal humerus fractures with a prosthesis does not give complete pain relief and results in impaired shoulder function.