Interstitial pneumonia (IP) is sometimes a fatal complication of rheumatoid arthritis (RA). We describe a patient with progressive rheumatoid interstitial pneumonia, who responded to intravenous intermittent cyclophosphamide (IV-CY) and cyclosporine (CsA). A 62-year-old man with rheumatoid arthritis was admitted to this hospital because of dyspnea. Examinations on admission revealed that he had active RA with vasculitis and IP Initially, he responded to high-dose corticosteroid therapy. A lung biopsy performed after initial corticosteroid therapy revealed diffuse interstitial pneumonia with marked infiltrations of macrophages into the air spaces. On corticosteroid therapy with prednisolone 30 mg/day, the IP became exacerbated and was refractory to the current high-dose steroid treatment. He responded to intravenous cyclophosphamide, but his IP remained unstable. After CsA treatment was started, a clinical remission was obtained. In this case, CsA was the most effective agent tried. Clinical and pathological considerations led us to speculate that activated alveolar macrophages played a crucial role in the pathogenesis of steroid-resistant IP in this patient, and that the clinical remission induced by CsA may have been due to its inhibitory effect on alveolar macrophages.