OBJECTIVE : We report on the development and accuracy assessment of a hybrid tracking system that integrates optical spatial tracking into a video pass-through head-mounted display. METHODS : The hybrid system uses a dual-tracked co-calibration apparatus to provide a co-registration between the origins of an optical dynamic reference frame and the VIVE Pro controller through a point-based registration. This registration provides the location of optically tracked tools with respect to the VIVE controller's origin and thus the VIVE's tracking system. RESULTS : The positional accuracy was assessed using a CNC machine to collect a grid of points with 25 samples per location. The positional trueness and precision for the hybrid tracking system were [Formula: see text] and [Formula: see text], respectively. The rotational accuracy was assessed through inserting a stylus tracked by all three systems into a hemispherical phantom with cylindrical openings at known angles and collecting 25 samples per cylinder for each system. The rotational trueness and precision for the hybrid tracking system were [Formula: see text] and [Formula: see text], respectively. The difference in position and rotational trueness between the OTS and the hybrid tracking system was [Formula: see text] and [Formula: see text], respectively. CONCLUSIONS : We developed a hybrid tracking system that allows the pose of optically tracked surgical instruments to be known within a first-person HMD visualization system, achieving submillimeter accuracy. This research validated the positional and rotational accuracy of the hybrid tracking system and subsequently the optical tracking and VIVE tracking systems. This work provides a method to determine the position of an optically tracked surgical tool with a surgically acceptable accuracy within a low-cost commercial-grade video pass-through HMD. The hybrid tracking system provides the foundation for the continued development of virtual reality or augmented virtuality surgical navigation systems for training or practicing surgical techniques.