This report is an analysis of 252 popliteal artery aneurysms (PAA) in 167 patients treated surgically at the University Hospital in Zurich during a 27 year period from 1965 to 1991. The predominance of male patients (95 percent) was consistent with that of other reports. PAA were bilateral in 51 percent of the patients and were associated with aneurysms at other sites in 38 percent. Atherosclerosis was by far the most common cause (98 percent). PAA were symptomatic in 75 percent of the patients, the predominant findings being ischemia from emboli, thrombosis or rupture. Primary amputation was required in 23 extremities. Surgical reconstruction with bypass was performed for 229 PAA. A secondary amputation was necessary in 18 limbs. The risk of complications from popliteal aneurysms, and the good results from surgical treatment suggest that a revascularization procedure in the asymptomatic stage should be recommended unless specific contraindications exist. We conclude that surgical treatment should be performed in symptomatic and asymptomatic PAA larger than 2 centimeters in diameter. Long term results of surgical reconstruction are improved if an autogenous saphenous vein is used and if reconstruction is performed before the occurrence of complications. Polytetrafluoroethylene prostheses should be used when an autologous saphenous vein is not available. The use of Dacron (polyester fiber) grafts is no longer indicated.