The paper describes the state-of-the-art of thrombohemorrhagic events and the results of studies conducted by Russian and foreign authors in the past 15 years. It shows the pathogenetic mechanisms underlying the identification of risk factors and the possibilities of its reduction and gives indications for the prevention of thromboembolic and hemorrhagic events in patients who have undergone elective surgery for malignancies at various sites. Particular emphasis is laid on patients with head and neck tumors who have undergone microsurgical autoplasty as a group at high risk for both thromboembolic and hemorrhagic events. The paper provides an algorithm for a differential approach to anticoagulant prevention in relation to surgical volume and additional risk factors.