Background: Although acute renal failure (ARF) is a frequent complication of severe leptospirosis, there are few studies on renal function recovery in the literature. The objective of the present study was to verify how and when renal function recovery occurs after leptospirosis ARF. Patients and Methods: 35 patients with leptospirosis ARF (plasma creatinine [P<sub>creat</sub>] ≧133 µmol/l at hospital admission) were prospectively studied during hospitalization, at discharge and 3 and 6 months after discharge. Creatinine clearance, fractional excretion of sodium and potassium, proteinuria and sodium proximal reabsorption were measured under normal sodium diet. Urinary pH and the ratio urinary to plasma osmolality (U/P<sub>osm</sub>) were measured 18 h after food and water withdrawal. All parameters were also measured in 18 healthy volunteers. Presence of laboratorial alterations usually found in leptospirosis were evaluated in the patients. Patients were divided in 2 groups according to their maximum P<sub>creat</sub> value during hospitalization: group 1 ( P<sub>creat</sub> >442 µmol/l, n = 21), and group 2 (P<sub>creat</sub> ≤442 µmol/l, n = 14). Results: All patients presented with jaundice, fever and myalgia. Bilirubin and creatine kinase were higher in group 1. Oliguria was observed in 11% of all patients and 49% required dialysis; all these patients were from group 1. All renal parameters were normal at the 6th month except U/P<sub>osm</sub> that remained lower than normal. The pattern of renal function recovery was similar in both groups except for urinary volume. Conclusion: After leptospirosis ARF, renal function recovery is fast and complete after 6 months, except for urinary concentration capacity.