A 69-year-old postmenopausal woman who was prescribed anastrozole for 10 months after surgical removal of her breast cancer, was referred to our hospital for acute renal failure. Because it was possible that her renal failure was related to her treatment with anastrozole, the treatment was immediately discontinued. After renal biopsy was performed to examine her renal failure, she was diagnosed as crescentic glomerulonephritis, probably related with the treatment of anastrozole. Twenty mg of oral prednisolone was administered daily after methylprednisolone pulse therapy(500 mg/day intravenous administration for three days). Her renal dysfunction was gradually improved. Renal dysfunction was considered to be a rare complication of anastrozole. Patients who are prescribed anastrozole should be watched carefully for the development of renal dysfunction.