In the present study, the incidence of upper extremity involvement and the primary lesion of the arm in Buerger's disease were investigated with special regard to arteriographic findings in the upper limb. Of 34 patients with Buerger's disease admitted to our hospital during the 12-month period from March 1977 to February 1978, in 31 cases (91 per cent) the existence of arterial obstruction of the upper limb was confirmed. From the results of arteriographic study in 78 arms, the primary lesion of Buerger's disease appears to develop most frequently in the digital arteries. However, it is possible for the disease to develop independently in the arteries of the hand, or in the radial or ulnar artery. Although the aetiology of Buerger's disease is not definitely known, it is suggested that repeated blunt injury to the hand or fingers is involved in the evolution of the disease as well as in the appearance of symptoms.