Object. The goal in this study was to investigate early diagnostic evidence, optimal therapeutic strategies, and prophylactic methods for slit ventricle syndrome (SVS) in patients with temporal lobe arachnoid cysts who received cyst-peritoneal (CP) shunts. Methods. Six cases of SVS in patients with temporal lobe arachnoid cysts who received CP shunts were treated by the senior authors in 2 institutions between January 2005 and January 2009. The radiological data, treatment process, and therapeutic results were reviewed retrospectively. Results. There were 4 boys and 2 girls, whose mean age at presentation was 4 years and 1 month. The main clinical symptoms were severe headache, nausea, vomiting, and decreasing eyesight. Radiological studies showed normal or slightly smaller than normal ventricles, and arachnoid cysts that had shrunk dramatically. The most effective treatment for SVS was to replace the original shunts with devices that had a programmable valve, or if this was unsuccessful, to replace the original shunts with ventriculoperitoneal (VP) shunts. All symptoms in these patients disappeared, and the mean follow-up duration was 24 months. Conclusions. The SVS presents more often in patients with hydrocephalus who undergo VP shunting. However, it is also a serious complication in patients with arachnoid cysts who receive a CP shunt. The SVS is not a single condition; rather, different pathophysiological conditions can underlie this complicated syndrome. Because there are no striking morphological changes on radiological studies of the SVS in the patients with CP shunts, it is not easy for this syndrome to be diagnosed in time and treated rationally. Misdiagnosis and delayed treatment usually occur. The use of programmable shunts or VP shunts to replace the original shunt is an optimal therapeutic choice. The use of low-pressure shunts to treat arachnoid cysts should be abandoned unless dictated by specific indications. (DOI: 10.31712010.8.PEDS10222)