Abstract Background Hydrocephalus develops in up to 90% of patients born with myelomeningocele. Although Endoscopic Third Ventriculostomy (ETV) is currently considered the preferred treatment for obstructive hydrocephalus, its results have been inconsistent in patients with myelomeningocele. This study focuses on clinical and radiological outcomes of ETV in children with hydrocephalus related to myelomeningocele. Methods Medical records of 18 paediatric patients with myelomeningocele submitted to ETV from 1998 to 2015, at the Centro Hospitalar S. João, Porto, Portugal, were retrospectively reviewed. Patients’ caregivers were contacted to evaluate their clinical manifestations prior and after surgery regarding Hydrocephalus and Chiari malformation’s symptoms. Control neuroradiological imaging of 9 patients was obtained and analysed. Success of ETV was defined by clinical resolution and radiological confirmation. Results ETV was successful in 8 of 18 cases (44,4%). Groups of patients were compared according to age at the time of surgery, with a 40% (2/5) success rate in new-borns and 50% (3/6) in children over 1 year old. Eight patients underwent ETV as a first option, with 37,5% success. Ten patients were submitted to the procedure after previous VPS (Ventriculo-Peritoneal Shunt), five for malfunction and five due to VPS infection with 60% and 40% success rates, respectively. Early post-operative complications occurred in 2 patients. Conclusions ETV can be performed in myelomeningocele and hydrocephalus’ patients, with success rates of almost 50%. A previous VPS, VPS malfunction or infection do not contraindicate ETV. If possible, the procedure should be delayed until the patient completes 1 month of age.