The renal function of eleven patients with mucocutaneous leishmaniasis was analyzed in a prospective study realized at the School Hospital of University of Brasília. The patients were treated with doses of 40 mg/kg/day of pentavalent antimony (Sb V), in a continuous scheme during thirty days. In this study three patients were excluded, one patient with reversible renal failure and two patients with hepatic and cardiac malfunctions. In the other eight patients, severe nephrotoxic effects were observed, like reduction of glomerular filtration rate, reduction of the urinary concentration capacity, evaluated by a sixteen hours hydric fasting and an increase of sodium fractional excretion. An increase in the number of leucocytes and cylinders were observed at the urinary sediment exam. Finally, the results shows that the treatment with pentavalent antimony in doses of 40 mg Sb/kg/day was less tolerated on account of its renal toxic effects. This scheme seems not be superior than the currently preconized scheme of 20 mg of Sb V/kg/day during 30 days.