BACKGROUND Reactive airways dysfunction syndrome (RADS), which represents between 5% and 18% of new-onset, work-related asthma, remains underreported in spite of increasing reports of occupational asthma cases through occupational asthma surveillance in Korea. We report a 61-year-old male who developed RADS after exposure to a high level of toxic gases from a workplace accident. CASE The patient who had worked for 21 years at a PVC manufacture factory and had retained good health until Aug 22, 2007, when he was exposed to PVC (polyvinyl chloride), DEHP (Di (2-Ethylhexyl) Phthalate), dibutyl tin maleate and epoxidized soybean oil gases from a heated mixer. Within several minutes of exposure, he developed coughing, rhinorrhea, dyspnea and wheezing. Pulmonary function tests (PFTs) showed an FVC of 3.81 L(82% of predicted), FEV1 of 1.63 L/s (50% of predicted), FEV1/FVC% of 43 %, and FEV1 of 1.80 L/s that increased by 170 ml and 10.4% in response to bronchodilator. After 7 months of treatment with inhaled steroids and bronchodilators, repeat PFTs showed an FVC of 6.56 L(143.5% of predicted), FEV1 of 3.21 L(99.3% of predicted), and FEV1/FVC% of 48.9%. A methacholine challenge test was negative at a concentration of 25 mg/ml. CONCLUSION RADS occurred due to exposure to raw material vapors or their thermal decomposition products.