Meperidine is widely used for pain control in the hospital setting. It is also known for its propensity to cause mental status changes in renally and hepatically impaired patients. A case is reported of a 37-year-old man with chronic renal failure maintained on peritoneal dialysis in whom delirium developed when he was treated with meperidine not only on one occasion but also on two subsequent admissions. The pharmacology of meperidine is reviewed and the implications of using the medication in patients with renal impairment are discussed.