In the 40 cases of cystic adventitial disease of the popliteal artery reported in the world literature, 20 patients have been treated by graft replacement with two of four synthetic graft failures and two of 14 vein-graft failures. Simple cyst evacuation has succeeded in all but two of 19 cases and reevaluation of cyst has succeeded in both of the evacuation failures. The condition causes severe calf claudication in young men, but does not progress to severe ischemia nor need for amputation, even with failure of arterial reconstruction. Etiology of the condition is obscure but may be related to cellular incorporation of mucin-secreting cells within the arterial adventitia.