Evidence of areas of increased attenuation density within lateral ventricles at computed tomography (CT) of the brain is a finding of acute or subacute intraventricular hemorrhage. The purpose of this case report is to describe a 14-year-old female who presented with an episode of complicated migraine. Brain CT showed an area of high attenuation density (35 Hounsfield Units) in the trigone and occipital horn of the right lateral ventricle, mimicking a blood-fluid level from subacute intraventricular hemorrhage. Magnetic resonance imaging (MRI) of the brain showed that this resulted from gray matter lining a deep calcarine fissure. A deep calcarine fissure may mimic intraventricular hemorrhage at CT. Correct CT and MRI interpretation allows to avoid invasive diagnostic tests including lumbar puncture or intra-arterial catheter angiography.