Objective: An abdominal pseudocyst (APC) is a distal catheter site-specific failure in patients treated with ventriculoperitoneal shunts. Few studies with more than 10 patients have been reported. The aim of this study was to analyze causes of peritoneal catheter revisions with special emphasis on revisions because of an APC. Methods: Pediatric patients with first shunt operation between 1982 and 1992 were included, and time, cause, and modality of peritoneal catheter revision were determined retrospectively. Results: One hundred thirty-eight patients were treated for hydrocephalus, and 112 patients received a peritoneal catheter during the follow-up. An APC was diagnosed in 14 (12.5%) patients, and 28 revisions were needed for its treatment. The rate of shunt infection in patients with APC was 50%, but bacterial examination of the pseudofluid culture revealed infection in only 3 patients. Age at first surgical procedure, type of first surgical procedure, and etiology of hydrocephalus were not associated with APC diagnosis. APC recurred in 4 patients. These patients had a catheter repositioning directly into the peritoneum as first surgical treatment. No recurrences were observed in patients with shunt externalization or replacement of the peritoneal catheter. Conclusions: An APC is a major long-term complication after ventriculoperitoneal shunt treatment. Although a sterile inflammatory response cannot be excluded completely, our results favor the hypothesis of low-level shunt infection. In both cases, the surgical consequences are the same. An infected APC should be treated as a shunt infection. Uninfected patients can be treated with shunt externalization and replacement of only the peritoneal catheter.