Placement of ventriculoperitoneal(VP) shunt is a worldwide accepted procedure for treatment of hydrocephalus. This procedure have various intra-abdominal complications, of which pseudocyst formation is a rare one. Common presentations of this complication are abdominal mass, abdominal pain, intestinal obstruction, and shunt dysfunction. In this paper, we report a case of 3 year-old boy with cerebrospinal fluid (CSF) pseudocyst of the VP shunt presenting with hyponatremic seizure. To the best of our knowledge, hyponatremic seizure has not been previously reported as a presentation of abdominal CSF pseudocyst in the literature. Our case has also the largest CSF pseudocyst with respect to body surface area of the child in the literature.