Infectious mononucleosis is a common systemic illness primarily invloving children and young adults and due apparently to the Epstein-Barr virus (EBV). Although the typical case is easily recogniged, unusual manifestations or serious complications occur frequently enough to pose problems in diagnosis and management. Neurologic complications are rare(1%). These nerologic complications may actually precede the full clinical picture or present as the sole manifestation of the illness, thereby causing a confusing clinical picture and delay in diagnosis. We have experienced a case of infectious mononucleosis associated with facial nerve palsy in a 22-months old female. She was admitted to the hospital with the fever, right facial nerve palsy and hepatosplenomegaly. The diagnosis was made on the clinical findings, immunologic findings and the typical findings of peripheral blood smear. On peripheral blood smear, atypical lympocytes with relative lympocytosis were seen. On Immunologic study EBV anti-VCA IgM titer was 1:20 and the IgG titer was 1:40. To our knowledge, this is the first report in Korea. So, we report this case and the brief literatures of infectious mononucleosis associated with neurologic complications and other viral diseases which caused facial nerve palsy.