The aim of this report is to introduce a simple modification to the free-hand frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles. In this technical note, we describe our experience with ventricular catheter placement in two children suffering from shunt dependent idiopathic intracranial hypertension using an image-guided instrument holder with a catheter guide. In both patients, the surgical procedure proved to be easy and accurate, with good initial clinical results. The use of an image-guided instrument holder is a modification to the free-hand frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles.