ONCEacute renal failure hasdeveloped theclinical course isremarkably similar whatever theaetiology, andcanconveniently bedivided into twophasesfirstly thephase ofrenal insufficiency andsecondly therecovery phase. Thelatter commences when renal function hasimproved sufficiently tocorrect thebiochemical abnormalities. Thephase ofrenal insufficiency Theclinical effects ofacute renal failure werewell described bySalisbury (1958). For5days signs and symptoms areusually absent except forincreasing anaemia, butbythe6thdaythepatient isnauseated andslightly confused, withimpaired memoryor moresevere mentalchanges. Bythe7thdaythe patient isdrowsy withhyperactive reflexes, andby the8thdayprogressive twitching andsomnolence develop. Convulsions andcomaoccur onorabout the10thdayanddeath follows shortly afterwards, commonly preceded byaconvulsion. Thistimescale varies considerably withtherate ofprotein catabolism (Parsons &McCracken, 1957), whichisinfluenced inturnbythecause ofrenal failure (trauma, surgery, etc.) andthepresence of complications (haemorrhage andinfection, etc.). In general, patients withablood urearising less than 30mg/100 mldaily will probably recover adequate renal function before requiring dialysis, whilst those witha bloodurearising faster than50-60mg/ 100mldaily (i.e. mostofthose whohavesuffered accidental orsurgical trauma orareinfected), will require frequent dialysis toprevent deathfrom uraemia anditscomplications. Fluids