Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis is a life-threatening disease characterized by rapidly progressive glomerulonephritis (RPGN) and diffuse alveolar hemorrhage (DAH). Glucocorticoids and immunosuppressants are commonly used to treat this disease but may induce irreversible side effects, particularly in elderly patients. We herein report the case of a 76-year-old woman with RPGN. After methylprednisolone pulse therapy, DAH occurred, and she required ventilatory support. After plasma exchange, her serum creatinine level improved, and she was discharged with home oxygen therapy. Immunosuppressive agents other than glucocorticoids were not required. In conclusion, plasma exchange with glucocorticoid therapy may be effective in treating severe ANCA-associated vasculitis in elderly patients.