Our patient is a 42-year-old woman with muscle paralysis, muscle weakness, and fever. On admission, a neurologic examination showed proximal and distal weakness in the leg. Serum creatine phosphokinase and serum myoglobin level were markedly increased (5600 UI/L and 5197 UI/L, respectively). There was no sign of renal failure. Nerve conduction study was negative. Serologic studies for virus titers showed the antibody immunoglobulin M cytomegalovirus. Muscle weakness and its paralysis, fever, and serum creatine kinase level gradually improved after the administration of methylprednisolone intravenous. Cytomegalovirus infection was thought to have played a central role in this case, leading to an acute but reversible peripheral muscle paralysis.