A 76-year old African-American male presented with profound renal failure within 2 weeks after a screening colonoscopy. Polyethylene glycol (PEG) was the sole oral preparatory agent. The significantly elevated lactate dehydrogenase (LDH) and biopsy findings were consistent with acute renal cortical necrosis (RCN). PEG is associated with AKI, but the exact mechanism is uncertain. PEG can be biodegraded to diethylene glycol (DEG), which is a nephrotoxic agent associated with RCN. Three months after presentation, the patient remains hemodialysis dependent.