We report a case of pulmonary fibrosis in a 32-year-old man, who had worked at a steel mill and who died of respiratory failure due to interstitial fibrosis despite vigorous treatment. He showed SLE-associated symptoms, such as pleural effusion, malar rashes, discoid rashes, arthritis, leukopenia, and positive antinuclear antibody and anti-histone antibody. However, he did not present anti-DNA antibody. A thoracoscopic lung biopsy showed interstitial fibrosis, chronic inflammation and a small non-caseating granuloma in lung tissues, which could be induced by external agents such as metals. The manganese concentration in the lung tissue was 4.64 µg/g compared to 0.42-0.7 µg/g in the controls. The levels of other metals, such as iron, nickel, cobalt and zinc in patient's lung tissue were higher than those in the controls. The patient was probably exposed to Si and various metal dusts, and the lung fibrosis was related to these exposures. Exposure to Si and metal dusts should be sought in the history of any patient with SLE, especially in a male with pulmonary signs, and if present, exposure should be stopped. In the meantime, steps should be taken to ensure that workers exposure to Si and metal dusts in all environments have adequate protection.