Four hundred seventeen young children who had ingested a potentially serious amount of acetaminophen were examined and treated in a national multicenter open study. Fifty-five had plasma levels in the potentially toxic range, and 43 had a full course of acetylcysteine treatment. Three of 417 patients had SGOT values consistent with a hepatotoxic reaction. In the children with toxic levels of acetaminophen those who had also ingested alcohol had significantly lower SGOT levels than those who had not ingested alcohol. Patients consuming acetaminophen who had also consumed miscellaneous other ingestants were significantly more likely to be lethargic than those who had not consumed other ingestants. The incidence of transient hepatotoxic effects is significantly lower in children with potentially toxic plasma levels than in adults with similar toxic plasma levels. There were no deaths in this series of children.