An 83-year-old woman presented with left flank pain and high grade fever. After left ureteral catheterization and intensive chemotherapy with hemoperfusion, surgical exploration revealed the lower pole branches of the renal vessels were obstructing the ureteropelvic junction (UPJ), and dissection of the vessels released the obstruction. An 82-year-old man presented with right flank pain. Angiography demonstrated UPJ obstruction caused by the lower pole branch of the renal artery. Arterial dissection with dismembered pyeloplasty resulted in improvement of obstruction. In both cases, the patients had a long history of hypertension with mild to severe arteriosclerosis. Arteriosclerosis associated with fixation of the UPJ, may be one of the important factors leading to progressive hydronephrosis in geriatric patients.