To describe the symptoms, signs, findings and prognosis in children suffering simultaneously from polyradiculoneuritis and myelitis. Retrospective review of eight patients aged 2 to 13 years out of 210 patients with polyradiculoneuritis reported from 70 hospitals. Diagnostic criteria for polyradiculoneuritis were: flaccid paresis with loss of tendon reflexes, increased CSF protein and slowing of nerve conduction velocity. Criteria for myelitis were: severe and persistent bladder dysfunction, a sharply defined sensory level and/or evolving spastic paresis, with or without myelitic changes in spinal MRI. In the disease's earliest stage it was difficult to differentiate polyradiculoneuritis with myelitis from classical GBS. However, onset was often unusually rapid compared to GBS. Five patients developed a sensory level and seven suffered from severe bladder dysfunction. Four of the six children studied showed focal myelitic changes in MRI. All seven children with sufficient follow-up remained with residual paresis and significant long-term motor deficits. Due to its severe long-term prognosis, polyradiculoneuritis with myelitis must be differentiated from classical GBS. In the disease's early stage, the detection of a sensory level, severe bladder dysfunction and an unusually rapid onset can be helpful. The effect of high-dose corticosteroids is not yet clear. After the acute phase, most children require extended rehabilitation.