PURPOSE: To evaluate whether the early pulmonary irradiation can prevent or decrease the pulmonary damage and contribute to improve ultimate survival in paraquat lung. MATERIALS AND METHODS: From Jun. 1987 to Aug. 1993, thirty patients with paraquat poisoning were evaluated. Fourteen of these patients were received pulmonary irradiation(RT). All of the patients ere managed with aggressive supportive treatment such as gastric lavage, forced diuresis, antioxidant agents and antifibrosis agents. Ingested amounts of paraquat were estimated into three groups(A: minimal < about 5cc, B: mouthful 5-50 cc, C: Large > 50cc). Pulmonary irradiation was started within 24 hours after admission(from day 1 to day 11 after ingestion of paraquat). Both whole lungs were irradiated with AP/PA parallel opposing fields using C0-60 teletherapy machine. A total of 10Gy(2Gy/fr. X 5 days)was delivered without correction of lung density. RESULTS: In group A, all patients were alive regardless of pulmonary irradiation and in group C, all of the patients were died due o multi-organ failure, especially pulmonary fibrosis regardless of pulmonary irradiation. However, in group B, six of 7 patients(86%) with no RT were died due to respiratory failure, but 4 of 8 patients with RT were alive and 4 of 5 patients who received pulmonary irradiation within 4 days after ingestion of paraquat were all alive though radiological pulmonary fibrosis. All 3 patients who were received pulmonary irradiation after 4 days after ingestion wre died due to pulmonary fibrosis in spite of recovery from renal and hepatic toxicity. CONCLUSION: It is difficult to find out the effect of pulmonary irradiation on the course of the paraquat lung because the precise plasma and urine paraquat concentration were not available between control and irradiation groups. But early pulmonary irradiation within 4 days after paraquat poisoning with aggressive supportive treatment appears to decrease pulmonary toxicity and contribute survival in patients with mouthful ingestion of paraquat who are destined to have reversible renal and hepatic damage but irreversible pulmonary toxicity.