Acute disseminated encephalomyelitis (ADEM) and Guillain-Barré syndrome (GBS) are distinct demyelinating disorders that share an autoimmune pathogenesis and prior history of viral infection or vaccination. Our patient is a 10 years with acute flaccid paralysis, quadriparesis (lower limbs affected more than upper limbs), generalized areflexia and urinary retention. He had difficulty in speech and drooling of saliva. He also presented with raised intracranial pressure with papilledema; then bilateral optic neuritis developed during the later course of illness. Based on the temporal association and exclusion of alternative etiologies, diagnosis of the association between ADEM and GBS was made. Electro-diagnosis (electromyography-nerve conduction velocity) and magnetic resonance imaging study supported our diagnosis. He improved remarkably after treatment with intravenous immunoglobulin and intravenous methylprednisolone.