Thirteen patients with hemodialysis-related shoulder arthropathy were treated either with arthroscopic synovectomy or with open surgery. Arthroscopic synovectomy was performed in eight patients who had shoulder pain, shoulder immobility or both but did not have cystic bone lesions. The therapy was effective for pain relief and improvement of shoulder function for six months but in 12 months the shoulder pain reappeared in most of the patients. Open surgery was done in 5 patients who, in addition to shoulder pain and immobility, had humeral head bone cysts. Resection of the deposited mass on the biceps tendon sheath, of hypertrophied synovium and bursa as well as curettage of cysts and calcium hydroxyapatite ceramic implantation were performed. The therapy was effective for pain relief throughout the follow-up period (12 months). No adverse effects were noted for either procedure. Resected specimens of the synovia contained amyloid as indicated by a positive Congo-red stain by light microscopy and the presence of amyloid fibrils by electron microscopy. Deposition of amyloid in the biceps tendon sheath, synovium and bursa and invasion of the humeral head by amyloid were observed upon open surgery. The results suggest that the resection of deposited material induces the improvement of the shoulder arthropathy.