Cranial magnetic resonance imaging in 28 systemic lupus erythematosus patients who had experienced 30 acute neuropsychiatric events showed focal brain lesions in 16 of 30 events (53%) and low brain volume (atrophy) in 20 of 30 events (67%). Definite focal lesions were significantly more frequent in patients with clinically localized neurologic deficits (8 of 8, 100%), or seizures (5 of 6, 83%) than in patients without such localizing signs (3 of 16, 19%). Many of these lesions were occult on intravenous contrast-enhanced x-ray computed tomography. In 2 patients, lesions in gray matter resolved within 2 or 3 weeks, in association with clinical improvement. Magnetic resonance imaging is an important technique for detecting the extent of brain injury in cerebral lupus.