Abstract: Objective: To investigate the clinical effects of proximal femoral nail anti-rotation(PFNA) in the treatment of type Seinsheimer Ⅴ subtrochanteric fractures.Methods: The clinical data of 89 patients with type Seinsheimer Ⅴ subtrochanteric fracture were retrospectively analyzed.The patients were divided into the observation group(48 cases) and control group(41 cases) according to the technique of internal fixation.The observation group and control group were treated with PFNA and Gamma nail,respectively.The operation time,intraoperative blood loss,perioperative blood loss,time of off-bed after operation,postoperative Harris hip score and postoperative complications between two groups were compared.Results: The patients were followed up for 10 to 18 months,the fractures arrived at the standard of clinical healing.The difference of Harris hip score before operation between the observation group and control group was not statistically significant(P>0.05),and the Harris hip score after operation in observation group was significantly higher than that in control group(P<0.01).The operation time,intraoperative blood loss,perioperative blood loss and time of off-bed after operation in observation group were significantly less than those in control group(P<0.01).The differences of the incidence of four kinds of complications between the observation group and control group were not statistically significant(P>0.05).Conclusions: PFNA is suit for treating the unstable type Seinsheimer V substrochanteric fractures,which is the ideal internal fixation material,and worthy of application in clinic.