We have studied the epidemiology of giant cell arteritis (GCA) hi an urban population in south central United States. The incidence of GCA in Shelby County, Tennessee for the years 1971 through 1980 was determined for the total population and for age-, sex-, and race-specific groups. Over this period 26 cases were identified. The average annual incidence was 0.35/100,000; This was increased to 1.58/100,000 for those over the age of 50. The incidence was 7 times greater in whites than in blacks and 7 times greater in females than in males. Clinical and laboratory features of the patients were reviewed and found to be similar to those in other populations. GCA is considerably less frequent in Shelby County, Tennessee than in other areas where similar epidemiologic studies have been performed. This difference can be accounted for only in part by racial distributions. Similar studies in southern geographic areas are needed to place our findings in perspective and point to specific factors which may have etiologic significance in GCA.