We describe a college football player and weight-lifter who unexpectedly developed rhabdomyolysis and nonoliguric acute renal failure (ARF) following arthroscopic knee surgery. There was swelling and pain without evidence of a compartment syndrome postoperatively. The patient reported that he was an avid weight-lifter and that he was taking up to 10 g/d of a creatine supplement during the 6 weeks prior to this surgery. His ARF resolved over several days, with a peak serum creatinine of 2.3 mg/dl and peak creatine kinase (CK) of 194,000 U/l, following administration of intravenous fluids, mannitol, and sodium bicarbonate. Given the rarity of clinically significant rhabdomyolysis with this type of operation, we suggest that the patient's use of creatine increased the risk of skeletal muscle injury due to ischemia from intra-operative tourniquet application.