An adolescent presented with headache and projectile vomiting and showed ataxia, dysarthia and nystagmus with normal cognition. A diagnosis of acute cerebellitis was made on the basis of computed tomography and magnetic resonance imaging findings. He developed seizures and had a rapid downhill course with death at 48 hours after admission. Clinically, patients of acute cerebellitis present with fever, nausea, headache and altered sensorium with cerebellar symptoms. Inflammation of the cerebellum compresses the brain stem and induces mental alterations. It is a rare pathology developing due to an infectitious cause, post-infectitious or post vaccination etiology. Many times it is not possible to identify the causative agent. Cerebellitis can be mild where recovery occurs in few weeks and no abnormalities are seen on diagnostic imaging studies. On the other end, severe cases have focal neurological deficits, altered consciousness, raised intracranial pressure and abnormal neuroimaging. Treatment should be tailored to individual needs according to presentation, severity, and etiology. We discuss clinical features, diagnosis and management of acute cerebellitis which is an important cause of acute cerebellar functional disorder in childhood.