Large vessels vasculitis includes two diseases : 1) giant cell arteritis, formerly known as Horton's arteritis and 2) Takayasu arteritis. In this article, we will describe and compare the epidemiology, pathogenesis, diagnostic criteria and medical management of both vasculitis. T helper (Th) 1 and Th17 responses, genetic links and the role of viral (varicella zoster) and bacterial infection (Mycoplasma pneumoniae or Chlamydia pneumoniae) will be discussed. Classification criteria, inflammation biomarkers and progress in imaging tools will also be described. Finally, we will review the medical management including corticosteroids, aspirin and biologicals.