Behçet's syndrome significantly increases mortality especially when seen in the young male, while it is less severe among females and the aged. In many patients, the condition abates with the passage of time. The main cause of mortality is large vessel disease, especially bleeding pulmonary artery aneurysms (PAA), almost exclusively seen among men. Central nervous system disease comes second. Interestingly, not much increased atherosclerosis is seen in Behçet's syndrome when compared to other inflammatory diseases. In controlled studies, there has been no increase in history of increased angina or myocardial infarction. Similarly, atherosclerotic plaque formation is not increased by ultrasound. On the other hand, intermittent claudication can be seen. However, this is not due to arterial involvement but due to venous disease of the lower extremities. Recently there has been a substantial decrease in mortality due to PAA thanks to prompt disease recognition and treatment.