As ingestion of chlorhexidine gluconate (CHG) usually causes relatively mild symptoms, this chemical has been considered safe. An 80-y-old woman with dementia accidentally ingested approximately 200 ml of Maskin (5% CHG) in a nursing home and then presumably aspirated gastric contents. She was intubated for airway protection in the nearest hospital and referred to our critical care unit because of hypotension and rapid deterioration of consciousness. Despite intensive treatment, the patient died of acute respiratory distress syndrome (ARDS) 12 h after ingestion. The serum concentration of CHG was markedly high, although CHG reportedly has poor enteral absorption. We suspect the CHG was absorbed through the pulmonary alveoli following aspiration, not from the gastrointestinal tract. CHG has the potential for fatal ARDS when aspiration occurs following ingestion.