Purpose: Paraquat, a globally used herbicide, is highly toxic to human beings. Hence, we reviewed some cases of paraquat poisoning in Korea. Methods: We analyzed the clinical and laboratory findings of 50 patients poisoned with paraquat retrospectively. The patients were admitted to the department of internal medicine in the Eumseong KeumWang hospital from January 2008 to December 2008. Results: Among 50 cases of paraquat poisoning, 28 cases were male. Twenty-four cases (48%) were over 60 years old. Fourty-nine patients ingested paraquat on purpose as suicidal attempts, while 1 patient underwent accidental ingestion. Seven patients swallowed less than one mouthful of paraquat, of which 4 patients survived. Eleven patients swallowed two mouthfuls of paraquat, of which 8 patients survived. Thirty-two patients swallowed over three mouthfuls of paraquat and they all died. Thirty-one patients with leukocytosis died. Twenty-one patients with metabolic acidosis died. Increased levels of blood amylase and glucose were related to high mortality, and increased level of blood creatinine was related to severe mortality. Hemoperfusions were accomplished in 27 patients of paraquat poisoning, of which 12 patients survived. Conclusion: Paraquat is a highly toxic herbicide. When patients arrive at the hospital, laboratory findings, urine paraquat concentrations, arrival time, and the amount of paraquat consumed must be considered for treatment plan.