Interstitial lung diseases are primarily attributable to occupational or environmental exposures to dusts and irritants. We report on a case of interstitial lung disease, possibly secondary to iron exposure. Our male patient presented with cough and shortness of breath of more than 20 years’ duration after his occupational exposure had ended. A chest radiograph showed patchy shadows throughout both lower fields, and computed tomography showed ground-glass-like opacification, with fibrosis in the lower lobes. A lung biopsy revealed foamy cells in the alveolar spaces, with bronchiolitis obliterans. Microelemental analysis showed an increased level of iron in the lung tissue. After treatment with N-acetyl cysteine effervescent tablets, the patient's symptoms gradually improved. This probable case of iron-induced interstitial lung disease suggests the importance of obtaining a patient's history of occupational and environmental exposures for the sake of an accurate diagnosis.