A 69-year-old Japanese man suffered from bronchial asthma, atrial fibrillation, general fatigue, high fever, and weight loss of about 5 kg within a month. He also had intermittent claudication, a tingling feeling in his fingers and toes, and an ulcer on his toe. His laboratory data revealed leukocytosis with absolute eosinophilia. The patient was treated with predonisolone 30 mg daily. Although the ulcers healed once, the lesions recurred with tapering predonisolone. The patient visited us because of the ulcer on his toe. Physical examination showed a 2 cm ulcer surrounded by slight erythema on his right fourth toe. Magnetic resonance angiography detected tapering stenosis of the medium-sized arteries in both legs. A biopsy from his myocardium showed the infiltration of eosinophils into the myocardium. The neuron conduction rate of his lower leg was slower than that of the normal control, demonstrating mononeuritis. From these findings, we diagnosed this patient as Churg-Strauss syndrome.