The term critical limb ischemia refers to a condition characterized by chronic ischemic at-rest pain, ulcers, or gangrene in one or both legs attributable to objectively proven arterial occlusive disease. Critical limb ischemia implies chronicity and is to be distinguished from acute limb ischemia. Its incidence is approximately 500 to 1000 per million year, with the highest rates among older subjects, smokers and diabetics. The rate of primary amputation ranges from 10% to 40%, and was performed only when no graftable distal vessels were present, or in neurologically impaired or hopelessly nonambulatory patients. Contrarily, in some highly specialized and aggressive centres about 90% of patients with CLI had an attempted revascularization. Furthermore, patients with critical limb ischemia have an elevated risk of future myocardial infarction, stroke and vascular death, 3-fold higher than patients with intermittent claudication. Therefore, due to its negative impact on the quality of life and the poor prognosis both in terms of limb salvage and survival, critical limb ischemia is a critical public health issue.