Thromboangiitis obliterans (TAO) and antiphospholipid syndrome (APS) share the clinical characteristics of arterial thrombosis and recurrent thrombophlebitis. Although the association of anticardiolipin antibodies (aCLa) and TAO has been previously recognized, the prevalence and the clinical impact of this association remains unclear. aCLa were measured by double ELISA in patients with TAO (n = 47), premature atherosclerosis (pASO) (n=48) and otherwise healthy individuals (n = 48). Antibody status was then compared to clinical presentation and outcomes in patients meeting the diagnostic criteria for TAO. The prevalence of aCLa was significantly higher in patients with TAO (36%) compared to either pASO (8%; p = 0.01) or healthy individuals (2%; p < 0.001). Patients with TAO and a high antibody titer tended to be younger and suffer a significantly higher rate of major amputations compared to those without the antibody (100% versus 17%; p = 0.003). Clinical features of TAO not significantly altered by the presence of aCLa included upper limb involvement, digital necrosis, superficial thrombophlebitis (or deep venous thrombosis). Protein C, protein S, and anti-thrombin III were normal in all individuals. TAO is associated with an increased prevalence of aCLa. The presence of a high antibody titer in these patients is associated with increased morbidity, including major limb amputation. In patients meeting the diagnostic criteria for TAO, screening for aCLa should be considered. Although attractive, the efficacy of chronic anticoagulation in this setting remains to be proven.