OBJECTIVE: External ventricular drain (EVD) is a fundamental neurosurgical procedure that is commonly performed by junior neurosurgeons. Expedient, successful cannulation of the ventricles can be lifesaving. Yet, the free-hand technique of EVD insertion is associated with significant malpositioning rates. This study aimed to improve EVD placement by junior neurosurgeons with the aid of a customized 3D-printed surgical guide. METHODS: A 3D-printed surgical guide was developed and customized to our institution's EVD insertion procedure. First-year neurosurgical residents were taught how to perform preoperative trajectory planning based on coronal brain images and how to use the surgical guide during the standard EVD insertion procedure. Number of passes, accuracy of EVD placement, operative complications, need for revision, and surgeon's experience with the guide were recorded. RESULTS: First-year neurosurgical residents performed guide-assisted EVD insertion in 14 patients. Significantly, 6 (43%) patients had ventricular anatomy distorted by midline shift. All surgeons achieved successful ventricular cannulation using the EVD guide on first pass (100%). Of 14 guide-assisted EVDs, 13 (93%) were optimally placed (Kakarla grade 1). Only 1 (7%) guide-assisted EVD was suboptimally placed (Kakarla grade 2). There were no intraoperative or postoperative complications and no EVD revisions. CONCLUSIONS: For inexperienced surgeons, the 3D-printed EVD guide can improve ventricular cannulation even in cases of altered ventricular anatomy. The use of 3D printing would also allow the guide to be widely adopted by other institutions worldwide.