Prepontine (or suprasellar) arachnoid cysts are uncommon in clinical practice and experience in their management may therefore be limited. Symptomatic cysts usually present with features of hydrocephalus due to obstruction of the third ventricle and aqueduct, and occlusion or partial obstruction of both foramina of Monro. Several treatment techniques have been used including stereotactic aspiration, microsurgical excision and shunting, but the best method of treatment remains unclear and the role of endoscopy is not yet established. We report our experience in a series of seven patients who had endoscopic treatment for prepontine arachnoid cysts; five were children under 15 years old who presented with delayed development and/or enlarged heads. The two adult patients, both of whom had insertion of shunts as children, presented with headache and vomiting due to shunt blockage. All patients improved following endoscopic cyst fenestration. There was no operative morbidity and there have been no relapses to date. Endoscopic fenestration of prepontine arachnoid cysts appears to be an effective method of treatment.