Stroke in systemic lupus erythematosus [published erratum appears in Stroke 1991 Mar;22(3):417] We investigated the clinical and pathologic characteristics of stroke in 234 patients with systemic lupus erythematosus. Thirteen patients (5.6%) developed cerebrovascular disease. Cerebral infarction was noted in eight, cerebral hemorrhage in two, and subarachnoid hemorrhage in three. In seven (54%) of these 13 patients, stroke occurred less than or equal to 5 years after systemic lupus erythematosus was diagnosed. Among the predisposing risk factors for stroke, hypertension was the most important. Lupus anticoagulant was detected in three (38%) and anticardiolipin antibody in three (43% of seven investigated) of the patients with infarction. Evaluation of the clinical manifestations and autoantibodies indicated that renal involvement and high titers of anti-deoxyribonucleic acid antibody were more frequent in the stroke group than in the non-stroke group. Autopsy studies on six of the patients with stroke revealed small infarcts and hemorrhages in all, but in no case was true angiitis observed. Libman-Sacks endocarditis was found in two of the three patients with infarction. In conclusion, the important contributory factor to the development of stroke in patients with systemic lupus erythematosus is considered to be hypertension mediated by immunologic abnormalities. Antiphospholipid antibodies and Libman-Sacks endocarditis are closely associated with occlusive cerebrovascular disease. 