We present two cases of interstitial pneumonia with anti-Jo-1 antibodies in the absence of myositis. The first patient was a 38-year-old woman and the second, a 59-year-old woman. Both patients were admitted to our hospital complaining of dry cough and dyspnea on effort. The diagnosis of interstitial pneumonia was made from chest radiography, computed tomography and surgical lung biopsy. Anti-Jo-1 antibodies, which were highly specific for polymyositis and dermatomyositis (PM/DM), were detected in both patients. However, the serum creatine kinase concentrations and electromyographic findings in both patients were normal, and no clinical signs (including muscle weakness, rash and arthralgia) were found. In the first patient, oral prednisolone (PSL) treatment (20 mg day) improved the interstitial pneumonia, but PSL has now been tapered to 17.5 mg day. In the second patient, oral PSL treatment (40 mg day) improved interstitial pneumonia, and the dose was tapered to 5 mg day. The second patient was followed for more than 10 years after treatment, but she has never shown any signs of clinical myositis. Further investigation will be required, because no pathophysiological relation between anti-Jo-1 antibodies and interstitial pneumonia with PM DM has yet been established.