A 47-year-old woman unwittingly ingested an unknown substance together with her breakfast coffee. She suffered effects such as strong headache, generalized cyanosis, and a burning sensation of the lips and collapsed some minutes later. After admission into hospital a methemoglobin level of 35% was determined in the blood. Treatment by administration of tolonium chloride (toluidine blue) resulted in complete recovery of the patient. The toxic agent was identified as aniline by GC with mass selective detection after organic solvent extraction and 11 h after ingestion the plasma aniline level was 0.13 mg/l. Acetanilide (0.79 mg/ml) and acetaminophen (2.3 mg/ml) were identified in plasma as metabolites of aniline. It was assumed that a high metabolic capacity for acetylation protected the victim from more severe reactions. Her husband confessed later that he had tried to poison her.