Critical hand ischemia (CHI) is a quite uncommon but highly disabling condition, generally caused by chronic occlusive arterial disease. For a correct approach to the endovascular treatment of these patients, good knowledge of the normal vascular anatomy and of the most frequently encountered vascular anatomical variations is of paramount importance. In the present paper a description of the normal vascular anatomy of the upper limb and of the most commonly encountered anatomical variations is provided, focusing on the implications for endovascular treatment of patients with CHI. Moreover, data of 151 patients with 172 critically ischemic hands treated at our institution between 2004 and 2016 are presented.