An acute cyanotic episode due to methemoglobinemia occurred in a 16-month old girl following the ingestion of N,N-dimethyl-p-toluidine, a commercially available component used in the production of artificial fingernails. The amount of the parent compound ingested was about 6 mg/kg of body weight. Administration of methylene blue was effective in the reversal of the methemoglobinemia. In vitro studies suggest that the activity of the compound was probably due to its biochemical transformation to the toxic metabolite p-methylphenylhydroxylamine. We expand the list of aromatic amino or nitro compounds and their derivatives capable of producing methemoglobinemia and call attention to the hazard of their ingestion.