We report a 7-month-old female infant with Miller Fisher Syndrome (MFS), presenting with external ophthalmoplegia, blepharoptosis, ataxia, and loss of deep tendon reflexes. We treated the patient with high-dose immunoglobulin therapy (400 mg/kg/day, 5 days), which yielded favorable recovery. Serum anti-Cytomegalovirus (CMV) IgM antibody was positive in the early stage of the illness; therefore, association with CMV infection was suspected. Serum tests for antibodies to gangliosides, including anti-GQ1b immunoglobulin G, were negative. Tachycardia and increased sweating, signs of autonomic dysfunction, were observed during the clinical course. Magnetic resonance imaging revealed enhancement of the cauda equina on day 13 of illness; however, this enhancement was no longer seen 4 months later. Miller Fisher Syndrome is thought to be a variant of the acute inflammatory polyneuropathies, such as Guillain-Barre Syndrome (GBS). GBS occurs widely in infants through old adults, but infantile MFS is rare, and to the best of our knowledge, our case might be the youngest reported case in the literature.