Cerebellar mutism (anarthria) is a well-described complication of posterior fossa tumor resection. It is accompanied by a characteristic behavior including irritability and autistic features. This syndrome is typically reversible within days to months. Underlying pathophysiology is unknown. We describe two children who presented with a similar clinical finding after nonsurgical cerebellar involvement, hemolytic-uremic syndrome in one and cerebellitis in the other. Postmortem pathologic findings in the first patient indicated cerebellar ischemic necrosis. Single-photon emission computed tomography in the second patient revealed diffuse cerebellar hypoperfusion with no supratentorial abnormalities, refuting a phenomenon of diaschisis between cerebellar and frontal connections. These findings confirm that this clinical syndrome may occur in a nonsurgical, nontraumatic context. They are consistent with recent integrative hypotheses explaining cerebellar anarthria.