Thromboangiitis obliterans (TAO), also known as Buerger's disease, is segmental non-atherosclerotic inflammatory disease, which affects the small and medium-sized peripheral arteries, veins and nerves of young adult smokers. The paper reports two TAO female patients, 26-year-old and 42-year-old, with prolonged clotting time. We compared 13 male patients and 2 female patients with TAO. The prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) were normal in the male patients, whereas the clotting times were prolonged in the female patients. Coagulation tests including PT, APTT and TT evaluation could be the potential markers to female patients with TAO.