Hydrocephalus and pseudotumour cerebri are a rare complication of Guillain-Barré syndrome (GBS), occurring in about 4% of the cases. The high concentration of cerebrospinal fluid (CSF) protein may lead to a decreased CSF absorption in arachnoid villi. A 10-year-old boy with GBS and hydrocephalus is presented. A mechanical ventilation was required 7 days after admission and he had been on the mechanical ventilation for 6 weeks. Lumbar puncture performed on admission revealed clear CSF with an opening pressure of 15 cm H2O and no cells, a normal glucose level and a protein of 240 mg/dl. He complained of headache and diplopia 11 weeks after admission. Fundoscopy revealed papilloedema, and bilateral mild abducens pareses were also detected. Magnetic resonance imaging displayed a communicating hydrocephalus and interstitial oedema. A ventriculo-peritoneal shunt relieved the symptoms of intracranial hypertension. In GBS, serial computed tomographic scans should be performed in patients with headache and papilloedema. Hydrocephalus may develop in GBS.