The present study investigated malnutrition in rats fed a diet deficient in proteins, lipids, vitamins and minerals, including sodium chloride. The renal function of malnourished 3-month old Wistar rats, assigned from weaning to the multideficient diet, supplemented or not supplemented with sodium chloride was evaluated. Compared with standard diet fed rats the groups maintained on the multideficient diet, regardless of the sodium content, showed body weight reduced by at least 58% and higher urinary sodium excretion. The rats on the multideficient diet not supplemented with sodium chloride exhibited low renal vascular resistance and high renal blood flow. In contrast, the rats on the multideficient diet supplemented with sodium chloride failed to show alterations in either the renal vascular resistance or in the renal blood flow. Although severe, the malnutrition was characterized by a negative balance of sodium that might have contributed with the renal vasodilatation seen when the content of sodium was low in diet.