Popliteal aneurysms are rare and tend to occur in older men with significant co-morbidity. Historically, management of popliteal aneurysms can be considered in three broad groups: (i) the technique of Antyllus; (ii) techniques relying upon a collateral circulation; and (iii) techniques involving maintenance or restoration of circulation. Bypass and exclusion is currently been challenged by endovascular techniques which show promise in selected cases. Current controversies in popliteal aneurysms management are: when to repair asymptomatic aneurysms, what operation to do and how to manage acute thrombosis. These have been addressed by studying, prospectively, 73 patients presenting with 116 popliteal aneurysms. Diameter greater than 2 cm is often stated as being an indication for elective operation in asymptomatic popliteal aneurysms. However, distortion of the aneurysm appears to be at least as important as size in determining whether symptoms are likely to develop. Of 17 popliteal aneurysms followed for a median of 34 months with a diameter 2-3 cm and distortion less than 45 degrees , none thrombosed. This is no worse than patency following elective bypass (P = 0.064). Popliteal aneurysms greater than 3 cm in diameter in patients who are unfit or who declined an operation were significantly more likely to develop thrombosis or any other symptom (P = 0.01 and P = 0.004, respectively). Popliteal aneurysms less than 3 cm in diameter with distortion less than 45 degrees can safely be managed by ultrasound surveillance. Popliteal aneurysms with greater diameter or distortion are best operated upon. Bypass, combined with proximal and distal ligation of the aneurysm, resulted in 5-year graft patency of 78% and 65% for popliteal aneurysms originally patent or thrombosed, respectively, with good long-term exclusion of the aneurysm. In addition to the general complications of intra-arterial thrombolysis, acute deterioration of the limb during lysis appears to be a particular problem when dealing with thrombosed popliteal aneurysms. It occurs in about 13% of cases which compares with 2% when dealing with thrombosed grafts or native arteries. Intra-arterial thrombolysis for thrombosed popliteal aneurysms is associated with unacceptably high numbers of complications and thrombolysis should be reserved for intra-operative use only.