To determine the long-term risks and benefits of a separate CSF reservoir in the management of 52 children (23 males, 29 females) with shunted hydrocephalus, a retrospective study was performed comparing the use and complications after separate reservoir insertion, with a prereservoir control period. Median age at first shunt insertion was 1 month and median age at reservoir insertion was 2 years 6 months. Median follow-up for shunt with the additional reservoir was 19 years 1 month. There was no mortality due to shunt failure nor CNS infection, and there were significantly fewer episodes of ventriculitis (p<0.01) and shunt blockage (p<0.0001) compared with the prereservoir period. There was no hemiplegia, epilepsy, visual, nor cognitive loss from the additional reservoir. The reservoir was used for access in 344 attendances (mean 6.62 attendances per patient) for diagnosis or treatment of raised pressure or CNS infection. It was concluded that a separate CSF reservoir is useful in the long-term management of patients with shunted hydrocephalus and is without mortality or significant increased morbidity.