Critical limb ischaemia (CLI) is the most severe manifestation of peripheral arterial disease (PAD). CLI is a clinical definition of the presence of ischaemic rest pain (analgesic drugs required for more than 2 weeks) associated or not with ischaemic lesions or gangrene, supported by objective tests (measurement of ankle and toe pressures). CLI is an important marker of severe and generalized atherosclerotic disease and recognizes the same risk factors (i.e. smoking, hyperlipidaemia, arterial hypertension, diabetes mellitus and age). The severity of CLI is confirmed by the high incidence of major amputation, disability and cardiovascular death. Diagnostic methods to study CLI are Doppler ultrasound, duplex ultrasound, computed tomography angiography (CTA) and magnetic resonance angiography (MRA), often essential for the decision-making of clinicians to plan best treatment. The treatment of CLI includes the correction of risk factors, best medical treatment. and revascularization (endovascular or surgical).