Abstract Objective: The geometry of the tibial plateau has a direct influence on the translation and the screw home biomechanics of the tibiofemoral joint. Little information on the relationship between the tibial slope and meniscal lesions is available. The objective of this retrospective study was to examine the effect of the tibial slope on the medial and lateral meniscus lesions in patients with intact ACLs. Materials and Methods: The MRIs and lat roentgenograms of 212 patients with meniscus lesions were examined to determine the possible effect of the tibial slope on meniscal tears. First, the anatomic axis of the proximal tibia was established. Then, the angle between the line drawn to show the tibial slopes (medial and lateral) and the line drawn perpendicular to the proximal tibial anatomic axis was established on MRI. The patients with previously detected meniscus lesions were classified into three categories: patients with only medial meniscal tear (Group 1, 90 patients); patients with only lateral meniscal tear (Group 2, 15 patients); and patients with both medial and lateral meniscal tear (Group 3, 19 patients). Group 4 had no meniscal tear (88 patients). The MRIs of the patients who had applied to the Orthopedic Outpatient Clinic with patellofemoral pain and no meniscal tear were included as the control group. Results: The average tibial slope of the medial tibial plateau was 3.18° in group 1, 3.64° in group 2, 3° in group 3, and 3.27° in group 4. The average tibial slope of the lateral tibial plateau was 2.88° in group 1, 3.6° in group 2, 2.68 in group 3, and 2.91 in group 4. The tibial slope on the medial tibial plateau was significantly larger than the lateral tibial plateaus in group 1 and group 4 (p<0.05). In group 2, there was no statistically significant difference between the tibial slopes of the two sides (p>0.05). In addition, the tibial slope on the lateral side of group 2 was significantly larger than that of groups 1, 3, and 4 (p<0.05). Conclusion: An increase in the tibial slopes, especially on the lateral tibial plateau, seems to increase the risk of meniscal tear.