Vascular lesions can be the presenting sign of Behçet's disease (BD) preceding classical symptoms. The aim of this study was to evaluate the prevalence and types of vascular involvement in BD. Among 2319 patients diagnosed with BD according to the criteria of the International Study Group for BD, 332 patients (279 male, 53 female) with vascular involvement were included in this study. Prevalence of vascular involvement was 14.3%. Vascular involvement was found to be more common in males (P<0.001, male:female ratio 5.26:1). Mean age at onset of vascular involvement was 30.58+/-7.88. Vascular lesion was the presenting sign of BD in 50 patients (2.1%), whereas in 109 patients (4.7%) it started together with other clinical symptoms at the age of diagnosis. Superficial vein thrombophlebitis (SVT) was the most common vascular symptom (53.3%) followed by deep vein thrombosis (DVT) (29.8%). Arterial lesions were rare (3.6%). Of the patients 13.3% had more than one type of vascular involvement. Lower extremities were the most frequent localization in patients with SVT, whereas the femoral vein was mainly involved in patients with DVT and the pulmonary artery was mainly involved in the patients with arterial lesions. In countries like Turkey where BD is more frequent, young male patients presenting with vascular involvement should be evaluated for BD.