A 15-year-old girl died 14 days after hemiplegia suddenly developed. On arteriography, intimai separation of the middle cerebral arteries showed as a long attenuated column of dye — the “string” sign. Pathologic examination showed intimai separation starting at the distal bifurcation of the right internal carotid artery and extending into the middle and anterior cerebral arteries. The arteriographic string sign as evidence of dissection may aid diagnosis of this cause of childhood hemiplegia. © 1975 American Academy of Neurology.