Six breast cancer patients were treated recently for renal insufficiency secondary to neoplasic involvement of the ureters. This complication usually occurs in long standing hormonal-dependent breast cancer with bone metastases. Diagnosis was performed by abdominal echography. Ureteral catheterization or percutaneous nephrostomy with or without irradiation always resulted in rapid recovery of renal function. Systemic chemotherapy could then be given, sometimes with antitumoral responses, allowing the removal of the endoureteral catheters.