Icterohemorrhagic leptospirosis is a zoonosis which is relatively frequent in rural agricultural or cattle areas. In the severe forms of the disease renal affection is frequent, but the incidence of acute renal insufficiency is far lesser. Three cases of acute renal insufficiency in adult male patients secondary to an infection by Leptospira icterohaemorrhagiae are presented. Two of the patients resided in urban areas and only one of which presented professional risk. The clinical polymorphysm of the illness is confirmed, having observed not only the absence of fever but also that of jaundice. The former history of chronic alcoholism, present in two cases, determined diagnostic difficulties with acute alcoholic hepatitis. The serologic diagnosis is often positive only at the end of the second week, and the need to carry out a series of seroaglutinations is to be insisted upon. The types of renal impairment in leptospirosis are reviewed and the presence of acute renal insufficiency is stressed, including those patients with less severe forms of the disease, and especially those without Weil's syndrome. All of the patients had to be treated with dialysis, although two of them had a conserved diuresis after an initial brief period of oliguria.