Concurrent meniscal repair with anterior cruciate ligament (ACL) reconstruction has shown good clinical outcomes, but it has a considerable risk of progressing to post-traumatic osteoarthritis of the knee. Here we investigated postoperative changes in the position of the lateral meniscus (LM) and assessed the short-term clinical results after concurrent LM repair with ACL reconstruction. Twentyseven patients underwent LM repair of a peripheral longitudinal tear concomitant with ACL reconstruction. We evaluated the preoperative and postoperative values of the Lysholm score and anteroposterior instability. The length and width of the lateral tibial plateau were determined by radiographic images. The length, width, body width, extrusion, and height of the LM were measured in magnetic resonance images and compared between the preoperative and postoperative measurements. Our analysis revealed that concurrent LM repair with ACL reconstruction improved the shortterm clinical outcomes. Although the body width and height of the LM did not change, the postoperative LM extrusion and LM width were significantly increased after the surgery. The post-traumatic transposition of the LM may not be completely prevented by LM repair concomitant with ACL reconstruction.