The association between cancer and thrombosis has been recognized for more than 150 years. Not only are patients with cancer at a substantially increased risk of developing venous thromboembolism (VTE), the link between several coagulation factors and tumor growth, invasion, and the development of metastases has been established. Reported rates of VTE in patients with cancer have increased in recent years likely reflecting, in part, improved diagnosis with sophisticated imaging techniques as well as the impact of more aggressive cancer diagnosis, staging, and treatment. Various therapeutic interventions, such as surgery, chemotherapy, hormonal therapy, targeted therapeutic strategies as well as the frequent use of indwelling catheters and other invasive procedures also place cancer patients at increased risk of VTE. The increasing risk of VTE, the multitude of risk factors, and the greater risk of VTE recurrence and death among patients with cancer represent considerable challenges in modern clinical oncology. The American Society of Clinical Oncology (ASCO) originally developed guidelines for VTE in patients with cancer in 2007. ASCO recently updated clinical practice guidelines on the treatment and prevention of VTE in patients with cancer following an extensive systematic review of the literature. Revised 2013 guidelines have now been presented and will be discussed in this review. Although several new studies were identified and considered, many important questions remain regarding the relationship between thrombosis and cancer and the optimal care of patients at risk for VTE. © 2014 Elsevier Ltd. All rights reserved. © 2014 Elsevier Ltd.