Abstract:[Objective] To introduce the surgical technique and preliminary clinical results of arthroscopic repair of medial patellofemo- ral ligament (MPFL) torn on patellar attachment secondary to acute patellar dislocation (APD) . [Methods] From May 2015 to September 2019, 30 patients with MPFL torn on patellar attachment secondary to APD received aforesaid arthroscopic repair. Two suture anchors were inserted on the medial edge of the patella, and then lumbar puncture needles punctured percutaneously, to pass through the femoral side MP- FL parallelly to the joint cavity. After that, the sutures attached on anchors were introduced out the skin on the medial side by loops through the lumbar puncture needles. Under arthroscopic vision, the sutures were tightened, and the patella track was evaluated, lateral retinacular release was added if necessary. As proper patella track achieved, the sutures were tied at last. [Results] All patients were successfully operat- ed on without serious complications such as nerve and vascular injury, and followed up for (26.10±9.70) months on average. By the time of the latest follow-up, all the patients got normal range of motion of the knee with no recurrent patellar dislocation and stiffness or dysfunction of the knee. The Lysholm score, patellar tilt angle (PTA) and patellofemoral congruence angle (CA) improved significantly in the latest fol- low-up compared with those preoperatively (P<0.05) . [Conclusion] This arthroscopic repair of MPFL torn on patellar attachment secondary to acute patellar dislocation does restore the patellofemoral stability and function, and is an effective treatment.