Acute disseminated encephalomyelitis (ADEM) and Guillain-Barré syndrome (GBS) are both rare post-infectious neurological disorders. The co-existence of these conditions has often been reported despite of low incidence. We describe a 20-year-old male, who presented with acute flaccid paralysis and encephalopathy. The patient showed reversible MRI lesions suggesting ADEM. This case showed anti-GT1a IgG and anti-GM1 IgM antibodies positivity. We suggest that certain immunogenicity within central and peripheral nervous system may share a common autoimmune process during the disease course.