Inflammatory bowel disease (IBD) is associated with an increased risk of vascular complications. The most important of these complications are arterial and venous thromboembolism, which represent a significant cause of morbidity and mortality in IBD patients. Recent data suggest that thromboembolism is a disease-specific extraintestinal manifestation of IBD. The most common thrombotic manifestations in IBD are deep vein thrombosis of the leg and pulmonary emboli. It has been suggested that disease activity and the extent of colonic localization are correlated with the risk of developing thromboembolism. The occurrence of thrombosis in patients with IBD is partially attributed to the existing hypercoagulable state in IBD. Both coagulation and fibrinolysis are activated in patients with IBD; this is especially true for those with active disease. The most common risk factors for thrombophilia in IBD patients with venous thromboembolism are Leiden mutation in the gene encoding factor V, hyperhomocysteinemia, and antiphospholipid antibodies. The main genetic defects that have been established as risk factors for venous thrombosis are rather uncommon in IBD, but when present increase the risk of thromboembolism. Screening for coagulation defects seems justified only in IBD patients with a history of thrombosis or a family history of venous thromboembolic events. Antithrombotic treatment of IBD patients with venous thromboembolism is similar to that of thrombotic non-IBD patients.