A previously healthy 13 year-old boy presented with acute-onset headaches, aphasia and right-sided hemiparesis. Imaging showed cerebral ischemic infarction due to bilateral carotid occlusion, and investigation for stroke etiology diagnosed homocystinuria. Homocystinuria is an autosomal recessive condition that affects the metabolism of the amino acid methionine due to an enzyme deficiency. This disorder involves multiple organs systems, and complications include thromboembolic events, ectopia lentis, mental retardation, and skeletal abnormalities. The early diagnosis and treatment of hyperhomocystinemia can significantly improve outcomes. Therefore, metabolic screening for homocystinuria is strongly recommended for children presenting with stroke.