Eosinophilic granulomatosis with polyangitis (EGPA) should be considered in asthmatic patients who present with severe systemic symptoms and eosinophilia. Progressive renal insufficiency can occur during the acute phase of EGPA accompanied by renovascular involvement. A 58-year-old man visited local clinic with complaints of malaise, weight loss, fever, and dyspnea. Eosinophilia was revealed in peripheral blood. Pulmonary function tests were carried out, which yielded decreased lung function with positive bronchodilator response. Kidney and skin biopsies were performed, and histological examination showed acute necrotizing crescentic glomerulonephritis and leukoclastic vasculitis in the skin, which led to a diagnosis of EGPA (Churg-Strauss syndrome) associated with rapidly progressive glomerulonephritis. The patient received pulse steroid therapy with parenteral methylprednisolone, followed by oral prednisolone. Clinical and laboratory findings improved dramatically, and remission was attained rapidly. The patient continued to be in remission for 5 months. Prompt and aggressive treatment with systemic corticosteroids is mandatory to control disease activity and to achieve remission.