PURPOSE: Paraquat is a chemical which causes death in 30~80% of patients even after ingestion of small quantities. In spite of much studies, there are no successful treatment modalities or predictive parameters for determining the prognosis of the poisoning. The aims of this study were to evaluate plasma-paraquat concentration and initial laboratory and clinical data as prognostic parameters in patients with paraquat poisoning. METHODS: A retrospective analysis by chart review was done on 168 patients over three years who had ingested paraquat.