Retroperitoneal fibrosis(RPF) is a disease in which fibrous tissues proliferate in retroperitoneal tissues and organs, including kidney, ureter, aorta, and inferior vena cava. Clinical presentations were not consistant, however, most of patients complain of nausea, vomiting, anorexia and back pain, flank pain, and abdominal pain. We report an RPF case that presented asymptomatic . A 59-year-old male patient was transferred to emergency room with elevated BUN and serum Creatinine (87.9 and 8.72 mg/dL) from local clinic. Blood Pressure and Heart Rate showed Respectively 156/96mmHg and 67 beats/min. In reviewing past-medical history, he had no diabetes and hypertension. The patient recently found an increase in serum creatinine(1.39mg/dL) in the population screening and was recommended to visit nephrology doctor. Non-enhanced CT findings showed both kidney hydronephrosis and left kidney atrophic change. The patient was performed percutaneous nephrostomy. On 7thadmission day, the level of serum creatinine was 5.87mg/dL. The patient underwent enhanced CT for evaluation for cause of hydronephrosis. Enhanced CT findings showed periaortic mass of soft-tissue density around lower abdominal aorta that retroperitoneal fibrosis. On 10th admission day, The patient was performed anterograde D-J catheter insertion. We planned steroid treatment for 6 month. On 15th admission day, prednisolone 1mg/kg was prescribed. On 16th admission day, the patient was discharged. 3 months after discharge, the level of serum creatinine was 2.26 mg/dL in outpatient clinic.