Giant cell arteritis (GCA) is a common vasculitis of unknown cause that affects persons in middle age and older. Its incidence rises with increasing age. The inflammatory lesions involve larger arteries that contain an abundance of elastic tissue. Although cranial symptoms such as headache, tender scalp, jaw claudication and visual symptoms are common, the disease presents in many different fashions, often with symptoms not directly related to the arteries. These latter presentations include fever, severe malaise, polymyalgia rheumatica, high erythrocyte sedimentation rate and anemia, thrombocytosis, sore throat, and hepatic dysfunction. GCA appears to have a self-limited course, but is also characterized by relapses and recurrences. Visual loss due to occlusion of the optic arteries is the most important early manifestation and aortic aneurysm is the most important late complication. Patients respond promptly to varying doses of glucocorticoids but drug side effects are common.