Thromboangiitis obliterans is a progressive, often relentless and devastating, vasculitis causing significant loss of digits and limbs in a youthful population of tobacco users. Whereas the specific pathogenetic mechanism has not been defined, tobacco use is clearly a trigger for what appears to be an autoimmune mechanism in a given group of patients. Its cessation almost always prevents further tissue damage. Medical and surgical therapy palliate accrued damage, but only complete abstinence from tobacco use allows stabilization of the process. An appreciation of the characteristic clinical, angiographic, and histopathologic features allows specific diagnosis and differentiation from premature atherosclerosis and other mechanisms of distal and microcirculatory deficits. There is a pressing need for the evaluation of agents that might interrupt this process in the face of continued tobacco use; such an agent would be helpful in combating proliferative arterial change in other types of vasculitis.