Fifty patients were treated for 52 mycotic aneurysms secondary to intravenous drug abuse. An initial misdiagnosis of cellulitis or abscess in 17% of the patients was corrected after arteriography or bleeding following operative drainage. There was no ischemia following ligation and excision of aneurysms of the radial, brachial, external iliac, deep femoral, and superficial femoral arteries. Excision of the common femoral artery in four patients and femoral bifurcation in 25 led to marked morbidity in 28 patients without simultaneous revascularization. Ischemia occurred in 53% of these patients; it was mild in 21% with claudication only. Severe, limb-threatening ischemia occurred in 32% and led to amputation in 21%. Six patients underwent artificial bypass, including one for absent back-bleeding at the time of ligation, four for immediate severe ischemia, and one for late ischemia. Two infected grafts were removed; another became thrombotic. Cultures were positive for 73% of aneurysms and blood of 46% of the patients.