Acute encephalopathy with thalamotegmental involvement occurs in infants and young children and is thought to be a postviral or postinfectious brain disease. This disease is preceded for several days by fever and symptoms of upper respiratory infection. The symptoms are followed by the rapid evolution of stupor and coma, associated with generalized seizures and decerebrate rigidity. In this disease, the computed tomography (CT) or brain magnetic resonance imaging demonstrate symmetrical focal lesions in the thalami and brainstem tegmentum. We report two cases of acute encephalopathy with thalamotegmental involvement and remaining motor dysfunction in infants.