SETTING: Multicentred hospital-based cases and control subjects in Korea. OBJECTIVE: To evaluate the association between idiopathic pulmonary fibrosis (IPF) and hazardous materials to which people are occupationally exposed. DESIGN: A multicentre, hospital-based, matched case control study was performed. The ratio of IPF cases to controls was 1:1 (n = 78 in each group). IPF cases and controls were matched in terms of age group, sex and place of residence. Conditional logistic regression analysis was performed. RESULTS: In simple logistic regression analysis, exposure to metal dust and any exposure for >1 year in an occupational setting were significantly associated with IPF (metal dust OR 4.00, 95%CI 1.34-11.97; any exposure OR 3.67, 95 %CI 1.02-13.14). After adjustment for environmental and military exposures and smoking history, the OR for metal dust exposure was 4.97 (95%CI 1.36-18.17) in multiple logistic regression analysis. CONCLUSIONS: Metal dust was associated with incident IPF in Seoul and Gyeonggi Provinces in Korea. This information will be used to support a tailored preventive strategy in specific industries or occupations.