Hospitalization for surgery has a high risk of developing venous thromboembolism, a condition that encompasses both deep-vein thrombosis and its potentially fatal complication, pulmonary embolism. Colorectal surgery implies a specific high risk for postoperative thromboembolic complications relative to other general surgery. This may be a result of pelvic dissection, the perioperative positioning of these patients, or the presence of additional risk factors common to this patient group, such as cancer, advanced age, or inflammatory bowel disease. The potential impact of venous thromboembolism and the need for effective thromboprophylaxis often are underestimated in these patients. Recommendations for thromboprophylaxis in colorectal surgery patients are based on the American College of Chest Physicians guidelines for thrombosis prevention in general surgery patients, with treatment stratified according to the type of surgery and additional venous thromboembolism risk factors present. Prophylaxis with low-molecular-weight heparin or unfractionated heparin is recommended for colorectal surgery patients classified as moderate to high risk. The small number of studies focusing specifically on colorectal patients, or on cancer or abdominal surgery patients with a colorectal subgroup, has shown that both low-molecular-weight heparin and unfractionated heparin can effectively reduce the incidence of venous thromboembolism. Low-molecular-weight heparin has the practical advantage of once-daily administration and shows a lower risk of heparin-induced thrombocytopenia. This review will assess the risk of venous thromboembolism in colorectal surgery patients and discuss current evidence-based guidelines and recommendations for prevention of venous thromboembolism.