Venous thromboembolism (VTE) is one of the most common and feared complications in surgical patients, and its prevention has been the subject of a Call to Action from the Surgeon General of the United States. Here, we review the literature on the use of risk assessment models for the stratification of surgical patients into risk groups to guide the administration of pharmacoprophylaxis. Despite some disagreement in the literature and among various guidelines, there is good evidence that risk stratification identifies a 7- to 20-fold variation in postoperative VTE risk among the overall surgical population, including patients at both low and high risk. This information is useful to providers who are making decisions about mechanical prophylaxis and pharmacoprophylaxis.