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[Background] Interstitial pneumonia sometimes develops with collagen vascular diseases (CVD), but interstitial pneumonia which does not fulfill the criteria of CVD at the time of diagnosis, that is, pulmonary involvement that precedes the onset of CVD, is often experienced. The usual interstitial pneumonia (UIP) pattern is most commonly seen in patients with rheumatoid arthritis (RA). [Rationale] Clinical differences between patients with idiopathic pulmonary fibrosis (IPF) and patients with pulmonary involvement clinicopathologically diagnosed with the UIP pattern that preceded the onset of RA (RA-UIP) were evaluated. [Methods] This retrospective study included 50 patients (31 men, 19 women) who were clinicopathologically diagnosed with UIP by video-assisted thoracoscopic surgery or at autopsy. During the course of the disease, five patients (one man, four women) were also diagnosed with RA. The remaining IPF patients were divided into 22 patients seropositive for one or more autoantibodies who were placed in the Seropositive group, and 23 patients seronegative for these autoantibodies who were placed in the Seronegative group. [Results] Median survival time in the RA-UIP group (107.6 months) was significantly longer than in the Seronegative group (26.6 months) and the Seropositive group (31.2 months). [Conclusion] Our results suggest that the patients with pulmonary involvement of the UIP pattern that preceded the onset of rheumatoid arthritis, have a better prognosis than IPF patients.