Hypertensive encephalopathy is believed to be caused by an abrupt elevation in systemic blood pressure. It rarely occurs in children and can be neurologically devastating if it is not recognized and treated immediately. This report describes an 11-year-old male who presented with edema and a cerebellar lesion, with acute obstructive hydrocephalus resulting from hypertensive encephalopathy. A shunt was inserted to relieve pressure in the acute stage. The patient's hydrocephalus and cerebellar swelling subsided when his blood pressure was controlled. The cerebellar lesion had been initially diagnosed as a glioma. In children, a cerebellar lesion occurring with acute obstructive hydrocephalus and hypertensive encephalopathy is rare but reversible. Clinicians should be aware of this condition because it might be misdiagnosed as a tumor of the posterior fossa.