Summary 1. The first case of cerebral coenurosis to be reported from the Western Hemisphere is presented. Cerebellar exploration revealed numerous daughter vesicles of a coenurus distributed along the brain stem of a twenty-six-month-old male infant with a history of sudden right hemiparesis, marked ataxia and symptoms due to an increase in intracranial pressure. 2. Postmortem examination of the brain revealed multiple, pedicellate, ramified and budding vesicles, which covered the ventral aspect of the pons, the medulla oblongata and the interpeduncular space. A coenurus, 3 cm. in diameter, with clusters of scolices arising from the germinal membrane was found, on frontal section of the brain, in the region of the left basal ganglia. A smaller cyst, 1 cm. in diameter, was located in the left frontal lobe. 3. The parasite in the brain of the infant was identified as the coenurus of Multiceps multiceps in accordance with the views of Clapham and other investigators.