Temporal artery biopsy is performed to confirm the diagnosis of giant cell arteritis. This proof is quite absolute and allows using corticosteroid treatment associated with considerable morbidity in elderly patients. Biopsy is necessary in patient supposed to suffer from giant cell arteritis. Treatment test, which is often difficult to interpret, is done only when temporal artery biopsy is impossible. The biopsy is easy, bilateralisation improves its efficiency. Sometimes the temporal artery biopsy allows to diagnose other vasculitides. Although this biopsy is easy, a strict clinical reflexion must precede its realisation.