To focus the attention on critical limb ischemia, high risk condition not for the limb only, but involving the survey of the patient itself.Etiology, diagnosis and therapy of arterial occlusive critical pathology (AOCP). Genetics and life style prophylaxis are shortly treated.AOCP is often asymptomatic pathology, underestimated by physicians themselves, though long-term death rate is the same between subjects affected by occlusive arteriopathy and cardiological failure.Interventional therapy, ranging from endovascular procedures (PTCA, stenting) to open surgery (by-passes, TEA, prostheses), remains the only effective weapon against critical acute limb ischemia, offering excellent revascularization rates (80-90%). Conservative treatment, comprehending thrombolysis, prostanoids and anticoagulant drugs recruit the role of invasive methods or are limited, alone, to ineligible patients. Genetics is still far from certain and durable results.AOCP is a long-term severe condition; multifactoriality and asymptomatology in a great number of patients, often justify misdiagnosed cases. In emergency the acute ischemia involves also demolitive surgery, with short and long-term poor prognosis.