Abstract:[Objective] To compare the clinical efficacy of elastic stable intramedullary nail (ESIN) versus proximal femoral locking compression plate (PFLCP) for femoral subtrochanteric fracture in old children. [Methods] A retrospective study was conducted on 33 old children who received surgical treatment for femoral subtrochanteric fractures in our hospital from January 2013 to January 2018. Based on the fracture type and instrument indication, 18 patients underwent ESIN, while the other 15 patients had fractures fixed with PFLCP. The documents regarding to perioperative period, follow-up and radiographs were compared between the two groups. [Results] All the patients in both groups had operation performed smoothly. The ESIN group proved significantly superior to the PFLCP group in terms of operation time, intraoperative bleeding, incision length, and hospital days (P<0.05) , although the former had significantly greater intraoperative fluo- roscopic frequency than the latter (P<0.05) . The postoperative follow-up lasted for more than 18 months in the two groups. There were no significant differences in the time to return walking and the time to resume full-weight bearing activity between the two groups (P>0.05) . Both the hip extension-flexion range of motion (ROM) and Harris score significantly increased over time postoperatively in both groups (P< 0.05) . The ESIN group was superior to the PFLCP group in terms of ROM and Harris score postoperatively, whereas which proved not sta- tistically significant at any matching time point (P>0.05) . Regarding to radiographic assessment, the ESIN group was significantly inferior to the PFLCP group in term of fracture reduction quality based on Baumgaertner criteria (P<0.05) , however, the ESIN group got fracture healing significantly earlier than the PFLCP group (P<0.05) . [Conclusions] Both ESIN and PFLCP are effective for internal fixation of fem- oral subtrochanteric fractures in old children, which should be selected according to patient's concreate condition and the instrument indica- tions.