Forty-four patients with polymyositis/dermatomyositis (PM/DM) were studied for precipitating antibody to Jo-1. Ten (23%) had anti-Jo-1 antibodies including 8 (47%) of 17 PM patients and 2 (15%) of 13 PM-overlap patients. None of the 11 DM nor 3 PM/DM-cancer patients had anti-Jo-1 antibody. Interstitial pulmonary disease was present in 5 (50%) of the 10 anti-Jo-1 positive compared to 5 (13%) of the 34 anti-Jo-1 negative patients (odds ratio = 5.8, p = 0.05). No differences in other demographic or clinical features or survivorship were noted between these groups. These data confirm the association of anti-Jo-1 antibody with an increased frequency of interstitial pulmonary disease in PM/DM patients.