The authors report an observation of peritoneal pseudocyst, complication of a ventriculoperitoneal shunt in a six month infant hydrocephalus, with spinal bifida. The literature review confirms the rarity of that complication (25 observations), always preceded by incidents of the shunt function, be it mechanical or infection. The pathogeny remains mysterious. It is probably a peritoneal reaction to infectious problems or stranger body reject. In therapeutic, except the evacuation of the pseudocyst by puncture or drainage by laparotomy, you must change the shunt utilizing the ventriculo-atrial shunt. It is necessary to keep obsession of an often latent infection that compels an external drain unit suitable antibiotics.