Fifty-two clinical charts of children who had been discharged from this hospital, after being treated for acute renal failure, were analyzed to determine the incidence, presentation and results of the treatment used. We found that 0.7% of the total number of children admitted developed this complication and that 4/5 of them were under two years old. The initial illnesses were gastroenteritis, bronchial pneumonia, cyanogenic cardiopathies and sepsis. Some of the patients had hypoxic episodes or went into hypovolemic shock or a combination of both. In half of the patients diagnosis was reached from anamnesis, from of oliguria, acidosis and nitrogen retention. In the rest from whom a urine sample was obtained, the diagnosis was confirmed when the FeNa was higher than 2 and because the U/P osmolarity and urea were under 1.3 and 5 respectively. The oliguric type of acute renal failure was seen in 65% of the cases; the non-oliguric type in 35%. In the first group the mortality rate reached 6.5% even though a third of them were placed under dialysis. Yet, in another 7 cases, dialysis could not be used because the child was in shock. Of the 18 cases of non-oliguric acute renal failure, 12 recovered; only 3 required dialysis. We conclude that the high mortality rate in cases of acute renal failure depends on the severity of the underlying illness, the age of the patient and the delay in the diagnosis of the disease. The use of dopamine and furosemide, as well as the application of hemoperfusion instead place of peritoneal dialysis in neonates with sepsis, could improve results.