Patients with Behçet's disease (BD) have been recognized to be at an increased risk of thrombosis and thrombotic complications have been reported in 12%-40% of patients. The precise pathogenetic mechanisms underlying the thrombotic tendency of BD are not known. In recent researches, it is reported that procoagulant mutations might play a role in thrombotic process in BD patients. We aimed to evaluate the frequency of activated protein C resistance (APCR) in our BD patients and to investigate the association between thrombophlebitis and APCR. The study included 116 patients with BD who fulfilled the International Study Group criteria and 70 healthy individuals as a control group. APCR levels were measured by the clotting method. APCR levels were 129.63 ± 39.70 and 152.26 ± 22.62 in BD patients and control group, respectively (P<0.01). APCR was found in 47.4% and 8.6% of BD patients and control group, respectively (P<0.01). There was no statistically significant difference regarding APCR levels between patients with thrombophlebitis and without thrombophlebitis (46.4% vs. 48.3%). We found the frequency of APCR to be increased in BD patients with or without thrombophlebitis. The lack of association between thrombophlebitis and APCR in our series of BD patients suggests that some factors like endothelial abnormalities other than thrombophilia play a major role in the pathogenesis of thrombosis in BD.