Nephrotoxicity manifested by renal insufficiency is a well-known consequence of aminoglycoside administration in hospitalized patients. We report a case of aminoglycoside-induced nephrotoxicity in a young woman with cystic fibrosis that illustrates the classical presentation of nonoliguric renal failure and the risk factors that predispose to the development of aminoglycoside renal toxicity. The incidence of aminoglycoside nephrotoxicity in cystic fibrosis appears to be lower than that expected for a population exposed to prolonged and repetitive courses of therapy with these agents. Cystic fibrosis is a unique disease in which the pharmacokinetic profile of many drugs is abnormal. The pharmacokinetics of aminoglycosides in cystic fibrosis are characterized by an increased drug clearance and a larger volume of distribution; why cystic fibrosis patients should exhibit these abnormalities remains an enigma. If, in fact, patients with cystic fibrosis have a resistant phenotype against aminoglycoside-induced renal damage; further research designed to investigate the complexity of the renal handling of these drugs in these subjects would contribute to unravel the molecular mechanisms of aminoglycoside nephrotoxicity.