Three patients with transient cerebellar dysfunction following head injury are described. Acute cerebellar signs, such as ataxia, nystagmus, and dysarthria, occurred just after trauma and resolved gradually, disappearing in every patient. Cerebrospinal fluid and computed tomography examinations were normal but magnetic resonance imaging and single photon emission computed tomography revealed cerebellar lesions. These findings distinguish cerebellar concussion from cerebellar contusion and suggest that the synergistic effect of trauma and ischemia may be the pathophysiological basis of this unusual syndrome.