Abstract:The Chiari malformations are a family of conditions characterized by developmental or, less commonly, acquired displacements of the cerebellum. The original 19th century description by Hans Chiari delineated 4 types, but only types 1 and 2 are more than just curiosities. In his initial description, Chiari classified the hindbrain malformations into type I, II and III and then latter added type IV malformation. Type IV is a very rare type. It is characterized by cerebellar hypoplasia or aplasia and tentorial hypoplasia. There is no hindbrain herniation in this type. We report a case of a 6 year old male patient who presented to us with a 6 year history of an occipitocervical mass and inability to stand and walk for one year and a 5 month history of headache and vomiting. CT scan of the brain showed a midline posterior fossa bone defect with a meningocele with active obstructive hydrocephalus and hypoplastic cerebellum without hindbrain herniation. A diagnosis of a posterior fossa congenital anomaly (Chiari 4) with obstructive hydrocephalus and occipito-cervical meningocele was made. Ventriculo-peritoneal shunt was inserted three days post admission. Patient was then electively taken to theatre five months later for repair of the occipitocervical meningocele.