High resolution computed tomographic (HRCT) scans were obtained in 215 patients with rheumatoid arthritis to assess pulmonary fibrosis (PF). We classified the HRCT appearances as five-point scale (0-4) based on the degrees of PF. The results were as follows: 1. We found 117 cases (54.4%) of PF on HRCT. 2. Patients with PF (grade 1-4) showed significantly increased leucocyte cell counts and significantly worsened pulmonary function test than patients without PF (grade 0). 3. Patients with advanced articular involvement had significantly higher prevalence of PF than others without them. 4. Patients who were previously or currently receiving gold sodium thiomalate (GST) injection or administration of methotrexate had higher prevalence of PF than others. However, patients who were receiving long term GST therapy (1 year long or sigma 1000 mg) had slightly lower prevalence of PF than others. This finding suggests that dose-dependent lung injury is not related to GST therapy. 5. Patients with advanced PF (grade 3, 4) had high prevalence of male sex, smoker, extraarticular manifestation.