Adverse effects of nonsteroidal antiinflammatory drugs are frequently seen because of the extremely widespread use of these agents. Nephrotoxicity is relatively uncommon with the drug ibuprofen and, when present, is usually rapidly reversible. Fatal acute renal failure from ibuprofen has never been reported. This is the case of a patient with multiple medical problems who had near-fatal acute renal failure after the ingestion of 36 g ibuprofen, and who required dialysis for several months, at which point renal function improved. He did not admit to ibuprofen ingestion at the time of admission, and some of the clinical manifestations, including anion gap metabolic acidosis, respiratory alkalosis, and mental status abnormalities, could be accounted for by renal failure. Hence, this diagnosis was not considered during admission. However, the patient admitted to ibuprofen ingestion after his mental status improved with hemodialysis. A number of other variables were present that probably contributed to the development of acute renal failure, such as the presence of long-term renal insufficiency, hypotension, and possibly other drug ingestion. Acute renal failure with massive ibuprofen ingestion may be fatal or may show delayed reversibility even after necessitating dialysis for several months.