Objectives: The aim of this study was to evaluate the accuracy of tibial tunnel placement using patient-specific three-dimensional (3D)-printed guides for repairing medial meniscus posterior root tears designed from magnetic resonance imaging (MRI) scans. Materials and methods: Five right fresh-frozen cadaveric knees underwent MRI scanning with 1-mm isotropic slices. For each specimen, custom guides were created to generate two transosseous tibial tunnels, with design based on anatomical landmarks including the medial tibial eminence (MTE) and the posterior cruciate ligament (PCL) insertion. Guide design was done using Rhinoceros software, segmentation of bone structures and soft tissues in 3D Slicer, and printing in polyamide. After arthroscopic repair, computed tomography scans and anatomical dissections were performed to measure the accuracy of tunnel placement relative to the native medial meniscus posterior root attachment (MMPRA), the MTE, and the PCL. Individual pre- and postoperative measurements were compared to verify anatomical accuracy, and pooled data from all knees were analyzed. Results: Individual evaluation showed minimal differences between pre- and postoperative measurements, ranging from 0.00 to 0.09 mm. Pooled analysis revealed no significant differences in the measurements taken: PCL-MMPRA (p=0.313), MTEMMPRA (p=0.705) or the width of MMPRA (p=0.125). The guides enabled precise and reproducible tunnel placement, with consistent targeting of the anatomical footprint. Each guide cost approximately €30, with a production turnaround time of less than one week. Conclusion: Patient-specific 3D-printed guides enable the effective creation of two anatomically accurate tibial tunnels for medial meniscus posterior root repair. This approach offers a rapid and precise solution for anatomical restoration using MRI-guided planning.