A randomized study was conducted on 66 patients with acute established oliguric renal failure. Intravenous doses of furosemide ranging from 1.5 to 6.0 mg/kg were given every 4 h to 33 of the patients; the remaining 33 patients served as controls. A persisting diuretic response was observed in 5 treated patients and in 2 controls. Hemodialyses were required in most of them. Furosemide did not significantly modify in cured patients the mean oliguric period, the number of dialyses and the mean period of renal insufficiency.