To review the association of thrombosis and vasculitis and discuss some of the proposed causal mechanisms.It is becoming increasingly evident that various systemic inflammatory diseases such as vasculitis are associated with an increased risk of both venous and arterial thrombosis. Increasing evidence supports the use of immunosuppression in the management of venous thrombosis in Behçet's disease. An increased incidence of thromboembolic disease in antineutrophil cytoplasmic antibody-associated vasculitis has been recognized, especially during periods of active disease. In addition, a higher risk of ischemic heart disease in these patients has also been observed. As in giant cell arteritis, recent evidence supports the role of aspirin in the prevention of ischemic events in Takayasu's disease.Thromboembolic disease is an important complication of several forms of systemic vasculitis, and it may result in significant morbidity and mortality. Many questions such as the role for screening of asymptomatic patients, prevention of thrombosis, and duration of anticoagulation in patients with vasculitis remain unanswered. Future studies exploring the mechanisms of thrombosis and its link to inflammation may provide insights in predicting patients at a higher risk for thrombosis and improve outcomes.