The plastic hardener methyl ethyl ketone peroxide (MEKP) is an unstable peroxide that releases free oxygen radicals. Ingestion of this compound induces widespread liver necrosis that is often fatal, extensive ulceration with subsequent scarring, and stenosis of the proximal digestive tract in survivors. Severe metabolic acidosis occurs due to the accumulation of formic acid and other organic acids inducing neurologic damage, such as optic nerve lesions. A 53-year-old man unintentionally ingested approximately 120 ml of a 33% solution of this compound in dimethylphtalate. The patient was treated with the free radical scavenger N-acetylcysteine to counteract free radical-mediated damage and with hemodialysis to remove accumulated organic acids. Although our patient demonstrated considerable edema and ulceration of the distal esophagus, stomach and duodenum in the acute phase, there was never any sign of liver damage or neurological damage, nor were there any demonstrable lesions in the proximal digestive tract three weeks after the event. Treatment with a combination of N-acetylcysteine and haemodialysis may be a promising therapy for this severe and potentially life-threatening intoxication.