Interstitial pneumonia of polymyositis and dermatomyositis (PM/DM), especially the rapid progressive type, is a serious complication. We report a case of acute exacerbated interstitial pneumonia associated with DM. The respiratory distress condition was refractory to steroid pulse therapy and cyclosporine, however, there was a good response to additional intravenous cyclophosphamide pulse therapy (IVCY). We propose the possibility that the combination of these immunosuppressants might be useful for interstitial pneumonia with DM which is resistant to conventional steroid therapies.