In this review we summarize the causes of cancer related thrombosis as well as modern treatment approaches. Malignancy as a risk factor for thromboembolism is becoming increasingly recognized by clinicians caring for these patients. The probability of thrombosis occurring in an individual patient is dependent on several factors, including accompanying medical problems, the type of cancer, the clinical stage, performance status, and the treatment modalities employed. Thrombophilia with a history of thromboembolism is important as well. The overall risk of thrombosis is sevenfold that of noncancer patients. Though much has been learned about the pathogenesis of cancer-related thrombosis, we are in fact just beginning to understand the cross-talk between cancer cells and their related microenvironment, and such investigations are likely to increase our knowledge of cancer-related thrombosis mechanisms. Research in these areas may also suggest new strategies for cancer prevention, metastasis suppression, and new treatments. Drugs used in cancer therapy are increasingly recognized to directly contribute to the thrombotic tendency. Few studies provide data on the optimal management of cancer patients with thrombosis. It has been learned that retreating with the same drug can be very hazardous. In general the approach to prevention of thrombosis is the same as for noncancer patients, recognizing that specific cancer types and stage can place a patient in a high-risk category. Initial coumadin therapy fails in a significant number of patients with cancer. Recognition of the cancer patients at highest risk for coumadin failure is challenging. Low-molecular-weight heparins appear to be more effective in such situations where coumadin is likely to fail or has failed, but these drugs are thought to be costlier. Newer agents such as Factor Xa inhibitors and TF inhibitors are currently under investigation and may be found useful in the management of cancer-related thrombosis.