We sent questionnaires to the major dermatological institutions in Japan concerning the course and associations of dermatomyositis (DM). Of 637 cases observed between 1973 and 1983, 68 were children. The mortality rate was 2.9% in children, 47.1% in adult males, and 30.0% in adult females. Associations with malignancies were noted in 30.1% of adults; 112 cases (19.7% of adults) died from these, but surgery improved the signs of DM in 22 cases. The main neoplasms were cancer of the stomach, lung, colon, and breast. Association with pulmonary fibrosis (PF) was observed in 85 cases (14.9% of adults) and, in spite of intensive treatment, 38 cases (6.7%) died from it. In the majority of PF cases who died within 2 months, pulmonary symptoms started within 6 months of the onset of DM. All cases of PF which occurred before the onset of DM survived. The concurrence of PF and malignancies was exceptional. Death from myocardial disease occurred in only 3 cases.