During the hemodialysis treatment of 543 uremic patients for 10 years, significant complications concerning metabolic calcium disturbances, subperiosteal resorption, calcification of soft tissue or peripheral vessels, and fractures were noted. Significant elevation of alkaline phosphatase was induced for 5 years under hemodialysis using 5.0--6.0 mg/dl dialysate calcium, but not under 7.5 mg/dl dialysate calcium. Plasma immunoreactive parathyroid hormone (iPTH) values were abnormally high with a few exceptions, without relationship to serum calcium levels. Among the patients with chronic renal failure on dietary control, osteomalacic changes were predominant, but their iPTH values were not always elevated. When the patients were treated for a long time with hemodialysis, the mixed type of osteomalacia and osteites fibrosa appeared. Administration of dihydrotachysterol and 1 alpha-hydroxycholecalciferol to the patients on hemodialysis changed the mixed type of osteomalacia and osteitis fibrosa to the osteomalacic type with the marked reduction of osteoid seam thickness.