The initial observations of dialytic support were brought from the laboratory and confined to patients with reversible acute renal failure. The thought at that time was one of short term maintenance. It was theorized that removal of waste products from the blood, albeit incomplete and inefficient, might allow these patients time to regenerate damaged tubules and regain renal function. After a dis­ appointing earlier experience in survival, greater sophisti­ cation and broader practice refined the dialysis skills and reduced mortality. It also became apparent that long periods of support were possible and successful attempts were then made in utilizing this technology in patients with chronic renal