Central venous catheters (CVCs) are commonly used in oncology patients. Up to 50% of CVCs are complicated by thrombosis within the catheter or the blood vessel. These thrombi are the result of local tissue damage, the catheter itself, and the thrombophilia of cancer. Frequent flushes with saline or heparin may reduce the frequency of catheter dysfunction but do not reduce the rate of deep venous thrombosis (DVT) in the catheterized blood vessel. Efforts to use prophylactic heparin or warfarin to reduce catheter-related DVT have not been rewarding.