Our hypothesis started from the discovery of the periodontal bacteria DNA in occluded arteries and phlebitis veins of Buerger disease. It was accelerated by the observation of platelets and bacterial coexistence showing aggregation of platelets. Using our hypothesis, we would like to explain the characteristic points of Buerger disease that have already been reported in various documents. Our hypothesis of Buerger disease is able to explain the signs and symptoms pretty easily. More investigations are necessary to understand the full story of the disease. The infection of the thrombus is the core of the disease. Angiitis is a secondary reaction of the intimal area.