We herein present two cases of cerebral infarction in the middle cerebral artery (MCA) territory associated with an accessory middle cerebral artery (AMCA), which is a rare anomalous vessel arising from the anterior cerebral artery that coexists with the main trunk of the MCA. Cerebral infarction occurred in both patients: due to occlusion of the MCA main trunk in one patient and occlusion of the AMCA in the other patient. These cases suggest the importance of recognizing an AMCA when interpreting neuroradiological findings in patients with MCA ischemic stroke, especially in the hyperacute phase.