We report a 46-year-old man who has sex with men (MSM) patient, of Scottish descent, who had no history of arterial hypertension, diabetes, or illicit drug use, was hepatitis C virus (HCV) negative but underwent right nephrectomy for urothelial tumor in 2006. Before starting antiretroviral therapy, he had a CD4 cell count of 316/mm(3) and plasma HIV RNA level was 1,020,537 copies per milliliter. He developed acute renal failure only 2 weeks after introduction of tenofovir-based antiretroviral therapy and then required 3 months of hemodialysis. After the end of hemodialysis, antiviral therapy was resumed with abacavir (300 mg×2/day), lamivudine (300 mg every day), and lopinavir/ritonavir (400/100 mg twice daily). Renal biopsy revealed severe and diffuse toxic acute tubular necrosis Two years after tenofovir discontinuation, the patient's renal function remained subnormal. Although severe renal toxicity due to tenofovir is rare, patients receiving tenofovir must be monitored closely for renal dysfunction especially during the first weeks of tenofovir therapy.