OBJECTIVES: Cancer patients receiving chemotherapy are at risk of venous thromboembolism (VTE). Information on anticoagulants use in these patients is lacking. This retrospective cohort study describes the patterns of anticoagulant use in this population using a US claims database.  METHODS: The MarketScan® databases, a nationwide database covering >30 million patients annually, were used. Adult cancer patients receiving chemotherapy ≤6 months following the cancer diagnosis between 2004-2010 were included. Patients with bleeding history before chemotherapy were excluded. Six cancer types were assessed: lung, colorectal, pancreas, bladder, stomach, and ovary. Anticoagulant use 2 weeks before or after chemotherapy initiation was determined using National Drug Code or Healthcare Common Procedure Coding Systems. Anticoagulant therapy duration was calculated as the sum of total injections administered and total days of supply from prescriptions dispensed within 2-weeks before/after chemotherapy initiation.  RESULTS: Overall, 30% (N=21,101) of the total patients (N=70,822) used anticoagulants within 2 weeks before/after chemotherapy. Of these, 34% used anticoagulants 2 weeks before only, 30% 2 weeks after only, and 36% in both periods. Users’ median age was 61 years and 49% were male. Users with a VTE history (12%) had a longer duration of anticoagulant use versus those without a VTE history. Of those with a VTE history, ~15% used anticoagulants for >2 months. The average/median duration of therapy was 15/2, 2.3/2, 19/12, 41/30 days for all users, users of unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), and vitamin K antagonist (VKA), respectively. Anticoagulant use was highest in colorectal cancer patients (40%) and lowest in bladder cancer patients (9%). Most commonly prescribed anticoagulants were UFH (75%), VKA (20%), and LMWH (8%).  CONCLUSIONS: Approximately 1/3 of cancer patients used anticoagulants around chemotherapy. Anticoagulant use varies by tumor type ranging between 9%-40%. Heparin was the most commonly prescribed agent and VKA had the longest therapy duration.