Clostridium septicum bacteremia is frequently associated with hematologic and colonic malignancies and neutropenia. It frequently produces 'metastatic' gangrene with excessive mortality. Standard therapy usually includes surgical debridement and antibiotics. We present a patient with metastatic breast cancer treated with high-dose chemotherapy and bone marrow transplantation. She was treated successfully with antibiotics alone despite developing Cl. septicum bacteremia and gas in hepatic metastases. The pathophysiology of this infection is reviewed.