Objective. Hemorrhagic cystitis is a well-known complication of cyclophosphamide therapy but extensive involvement of the entire urinary tract is far less common. We report here a patient who developed severe hemorrhagic pyelitis, ureteritis, and cystitis after one cycle of cyclophosphamide-containing combination chemotherapy.Method. A patient with synchronous carcinoma of the ovary and the uterus developed severe hemorrhagic pyelitis, ureteritis, and cystitis leading to bilateral hydronephroses and acute renal failure after one cycle of combination chemotherapy containing cyclophosphamide. The blood clots in the upper urinary tract were aspirated endoscopically and bilateral internal ureteric stents were inserted.Result. She underwent a prolonged diuretic phase with several episodes of hypokalemia, hypomagnesemia, and hypocalcemia and required intensive fluid and electrolytes replacement. Subsequently, she recovered fully with the ureteric stents removed 26 days later.Conclusion. In contrast to previous reports, where 2.8 g of cyclophosphamide was estimated to be the minimum cumulative dose required to cause hemorrhagic cystitis, this case illustrates that severe hemorrhagic complication can occur even after a low dose of cyclophosphamide (600 mg/m2, total dose of 846 mg). Prompt diagnosis and intervention may be life-saving.