Background and Aim: Ventriculoperitoneal shunt (VPS) is the most commonly used procedure for treatment of hydrocephalus in children. Abdominal cerebrospinal fluid pseudocyst is a rare complication but potentially fatal. The pathogenesis of this complication remains unclear. This complication should be considered during differential diagnosis of an abdominal mass. Our aim is to report how large and giant an abdominal cerebrospinal fluid pseudocyst can develop, and how severe the neurological damage can be. Case Presentation: A 6 year-old girl known to have a ventriculoperitoneal shunt presented with abdominal distension and signs of increased Intracranial Pressure (ICP). Ultrasonography revealed a hypoechoic intraperitoneal fluid containing cyst with a well-defined margin and septations. Abdominal computerized tomography revealed a huge cyst in the abdomen and the distal part of the peritoneal shunt tube located within the cyst. Laparotomy revealed a huge cyst extending from the upper right side of the abdomen to the pelvis. The whole cyst was excised and the catheter repositioned. Conclusion: Early diagnosis of abdominal Cerebrospinal Fluid (CSF) pseudocyst is only possible through close and periodic examination of patients after the procedure.