The therapeutic effect of steroid hormone(STH) against pulmonary fibrosis was evaluated in 6 patients with dermatomyositis(DM), 6 with progressive systemic sclerosis(PSS), 3 with rheumatoid arthritis(RA) and 5 with idiopathic pulmonary fibrosis(IPF). Of these patients, 7 were male and 13 were female. The average age was 46.5, ranging from 24 to 66 years old. Dosage of STH varied between 10mg and 40mg/day in each patient and the mean administration period was 14 months. Clinical effects were determined using chest X-ray film, % VC, PaO(2) and direct questioning. Twelve out of 20 patients improved after STH therapy. The clinical effectiveness of STH depended on the ground disease of patients with pulmonary fibrosis; that is, STH was most effe...