Two cases of amylnitrite poisoning are presented. In both cases, severe methaemoglobinemia developed after ingestion of approximately 10 ml of amylnitrite. When admitted to hospital, both patients were deeply cyanosed, and arterial blood samples were noticed to be chocolate brown. They were intravenously treated with methylene blue. Within one hour the condition of both patients had improved dramatically, and blood gas-samples had normalised. In cases of cyanosis with no obvious genesis, poisoning with amylnitrite should be considered.