This is a report of our experience with ventriculo-peritoneal shunting, the treatment of congenital and secondary hydrocephalus. It includes a detailed listing of all complications and an analysis of the number of complications per patient and per procedure in patients in whom either a three-piece or a one-piece shunt system has been inserted. A total of 161 patients were in the one-piece series and 196 patients in the three-piece series, with the follow-up being a minimum of 6 months. There were 598 procedures in 196 patients in the three-piece series and 302 procedures in 161 patients in the one-piece series, so that the average number of operations per child in the three-piece series was 3.1 and only 1.9 in the one-iece series. There were 106 instances of ventriculitis in the three-piece series only 22 in the one-piece series, and 47 non-ventriculitis related complications in the three-piece series, but only 17 in the one-piece series. Data are presented descriptively with listing of specific complications and as computer analysis statistical printouts for categories (disconnections, infections, obstructions) comparing the three-piece and one-piece systems.