Acute cerebellitis is one of the main causes of acute cerebellar dysfunction in childhood and may be infectious, postinfectious, or postvaccination. The etiology of acute cerebellitis is usually viral. Varicella zoster, Epsten-Barr, rubeola, pertussis, diphtheria, and coxsackie viruses are the most frequently involved agents. Diagnosing of acute cerebellitis can sometimes be difficult because the patient may present only mild cerebellar signs and the examination of cerebrospinal fluid may be normal. The authors present the clinical and neuroimaging findings of 2 patients presenting with acute cerebellitis. Their magnetic resonance imaging showed hyperintense signal of cerebellar gray matter in T2-weighted sequences, which is a strong indication of a diagnosis of acute cerebellitis.