The clinical and autopsy findings in a premature baby who died of acute renal failure after therapy with gentamicin (5 mg/kg/day) and penicillin are presented. The serum gentamicin concentration had reached toxic levels when anuria developed. Numerous periodic acid Schiff (PAS) positive, diastase resistant cytoplasmic inclusion bodies which appeared as myelin figures in cytosegresomes under the electron microscope were identified in the proximal convoluted tubules. The pathological changes induced by gentamicin in the human neonatal kidneys have not been previously reported.