Cervico-oculo-acoustic (COA) or Wildervanck syndrome is characterized by the triad of Klippel-Feil anomaly, bilateral abducens palsy with retracted bulbs (Duane 'syndrome') and hearing loss. The clinical findings of this syndrome have been well documented. A few case reports with MRI findings have appeared in the literature showing brainstem and cerebellar hypoplasia and vertebral segmentation anomalies. Our case is unique in that diastematomyelia of the lower medulla and cervical cord was accompanied by vermian hypoplasia, tonsillar herniation and resulting triventricular hydrocephalus in a child with Wildervanck syndrome. This case is presented with MR images. Children with Wildervanck syndrome should be investigated for craniospinal abnormalities with MR imaging.