A 44-year-old woman visited our hospital in August 1997 with complaints of general fatigue and low-grade fever. Initial examination disclosed slightly elevated muscle enzymes and inflammatory reactions. A diagnosis of dermatomyositis was made on the basis of findings of skin symptoms consistent with Gottron's signs and a slight decrease in muscular strength. Reticular shadows were observed in both lower lung fields on chest X-ray films, and examination of transbronchial lung biopsy specimens revealed interstitial pneumonitis. After 1 course of steroid pulse therapy, the patient was placed on a regimen of prednisolone (PSL) at 60 mg/day and cyclosporin (CsA) at 200 mg/day. Although her skin symptoms and interstitial pneumonitis temporarily subsided, aggravated interstitial pneumonitis and elevated blood LDH levels were observed as the steroid dose (PSL) was being tapered. After a second course of steroid pulse therapy, the PSL dose was increased to 50 mg/day and CsA was replaced by methotrexate (MTX), at 7.5 mg/week. This brought the patient's interstitial pneumonitis under control. Although our patient had dermatomyositis complicated by interstitial pneumonitis which belongs to the group of poor prognosis, she responded favorably to combination chemotherapy with low-dose MTX.