Background and Aims Gentamicin is an aminoglycoside antibiotic widely used for the treatment of many infectious diseases. Its main side effect is its nephrotoxicity, which occurs in 10-25% of therapeutic courses, despite proper monitoring and hydration of patients, can lead to acute kidney injury (AKI). We have previously demonstrated that urinary damage markers like albuminuria increased as a consequence of the addition of gentamicin. In the present work we aimed at specifically studying the renal handling of albuminuria in a nephrotoxicity model, through in situ renal perfusion experiments. Methods Male Wistar rats were administrated by a single dose of gentamicin (150 mg/kg), or not. After 5 days, rats were anesthetized and an extracorporeal circuit for kidney perfusion was set up. The renal artery, vein and ureter of the right kidney were ligated. The renal artery of the left kidney and the urinary bladder were canulated. A catheter was placed in the right carotid artery and connected directly to the renal artery. Urine was continuously collected from a catheter placed in the urinary bladder at 10 min intervals. After 1 h of renal perfusion with blood from the carotid artery, oxygenated and warm (37 °C) Krebs-dextran (40 g/L of dextran) was perfused through the renal artery at 3 mL/min, and was discarded through the renal vein. Albuminuria was measured in the different urine fractions.