IgG and IgM isotypes of anticardiolipin (aCL) antibodies were measured in a group of 40 patients with biopsy-proven temporal arteritis (TA), 13 of them with ischemic complications related to the disease. High levels of aCL antibodies were found in only 3 (7.5%) patients. Two had high titres of both IgG and IgM isotypes and the third had high titres of the IgM isotype. No relationship between aCL antibody positivity and the development of any of the classical early occlusive complications of TA was found. However, 2 out of the 3 patients with positive aCL antibody titres later developed ischemic phenomena on conventional corticosteroid treatment. This finding suggests that aCL antibodies could perhaps have a role in the development of the late ischemic complications that occasionally occur in adequately treated TA patients.