BACKGROUND: Ultrasound guidance offers real-time visualization of patient-specific anatomy during external ventricular drain (EVD) insertion. A craniectomy defect provides a sonolucent window, enabling the use of a large, low-frequency probe with deep penetration and a wide field of view. While specialized burr-hole probes exist, use of a curvilinear probe through a craniectomy defect for bedside EVD placement has not been previously described. METHODS: Using a curvilinear probe, we performed ultrasound-guided bedside insertion of a left frontal EVD through a hemicraniectomy flap. RESULTS: Bedside ultrasound enabled visualization of the entire supratentorial ventricular system. Drain insertion was successfully performed, with immediate sonographic visualization of the catheter tip in the left frontal horn. Placement was confirmed with a computed tomography scan. CONCLUSIONS: Bedside ultrasound-guided EVD insertion in post-craniectomy patients can be a valuable method for safely accessing the ventricle in the face of abnormal or distorted anatomy.