Operative repair was undertaken for 51 popliteal aneurysms in 39 patients between 1958 and 1990. Operation was performed on an emergency basis in 19 extremities with limb-threatening ischemia and as an elective procedure in 32 extremities. Cumulative limb salvage (94%) rates and patency rates (67%) became significantly different at 6 years (p less than 0.05). Graft patency was affected by clinical presentation and runoff. After 1 year, cumulative patency for extremities with limb-threatening ischemia was significantly lower than for those having an elective operation (69% vs 100%, p less than 0.05). Runoff did not influence graft patency until 3 years, at which time cumulative patency was better in extremities with good runoff than in extremities with poor runoff (89% vs 30%, p less than 0.05). Limb salvage was affected only by presentation. All limb loss (three patients) occurred within the first month in extremities with graft occlusion after operation for limb-threatening ischemia. Runoff did not influence patency rates for extremities with limb-threatening ischemia, since no difference was observed in runoff between the two groups. We conclude that elective repair is indicated in all patients with popliteal aneurysms. It is associated with little risk to the patient, and prevents the need for operation in the setting of limb-threatening ischemia with its poorer overall results and definite incidence of amputation.