We studied 14 cases of polymyositis-dermatomyositis (PM-DM) and found roentgenographic evidence of interstitial lung disease in 9 patients with DM (64.3%). Serum anti-Jo-1 antibody was demonstrated in only one case. Histologically, interstitial pneumonitis and fibrosis were noted in all cases. Deposition of immunoglobulins along the alveolar interstitium was not found in any case. Response to corticosteroid therapy was poor, and 6 cases (67%) succumbed to respiratory failure and died. We conclude that interstitial lung disease in DM occurs more frequently than previously reported and may be an important prognostic factor.