Acute cerebellitis is a severe neurological disease characterized by mild or high-grade fever,nystagmus, tremor, truncal ataxia, dysarthria, headache, and altered mental state. Thediagnose can be established on the basis of clinical symptoms, radiological imaging andlaboratory findings. Acute life threatening hydrocephalus can be seen as a complication ofacute cerebellitis associated with obstruction at the level of the fourth ventricle. Neurosurgicalprocedures as a life-saving intervention can be required which range from external ventriculardrainage to ventricular peritoneal shunt and posterior fossa decompression. In this report wepresent a case of cerebellitis and concomitant acute hydrocephalus in a child which wastreated succesfully with external ventricular drainage and medical treatment and also discussthe main features of this rare but important concomitance.