Psoas abscess with aortoiliac infection is rare. Patients are often symptomatic for a long time before the correct diagnosis is made. The authors report 4 cases in which the presenting symptom was an antalgic flexion of the left thigh. In 2 patients the cause was an aortic graft infection with enteric fistula; in the other 2, infection developed after transfemoral endovascular procedures. Open surgical treatment was performed in 3 cases and percutaneous drainage in 1. One surgical patient with a late diagnosis eventually died of sepsis; the other 3 are alive and well at mean follow-up of 14 months.