We studied chest X rays of 911 patients with rheumatoid arthritis (RA). The findings showed interstitial shadow in 28 patients (3.1%), pleuritis in 13 patients (1.4%) and nodular shadow in 3 patients (0.3%). RA patients with interstitial pneumonia were commonly male and older. And they had significantly high levels of rheumatoid factor (RF), RAPA and IgG-RF in serum, but they were not associated with high score of Lansbary index. All patients with more than 1500 IU/ml in RF value had a complication of interstitial pneumonia. These results suggest the importance of chest X-ray in the management of RA patients with high titer in RF.