Background and objectives: Endoprosthesis is considered a durable implant for treating metastatic bone disease of the proximal femur (MBDf). Objectives: • What is the revision risk after surgery for MBDf using endoprosthesis versus internal fixation? • When do patients with MBDf treated with endoprosthesis restore quality of life (QoL) and how long time does it take to rehabilitate functional outcome? Methods: A prospective, population-based, multicentre study of 110 patients. Patients were followed for a minimum of two years after surgery. No patients were lost to implant failure nor survival follow-up. Results: Forty-four patients were treated with internal fixation and 66 patients received endoprostheses. Two-year implant failure risk for internal fixation was 7% (95CI: 0–14%) versus 2% (95CI: 0–5%) for endoprostheses (p = 0.058). Eq-5D improved to the same level as one month prior to surgery six-weeks after surgery, and the score improved further six months after surgery (median score from 0.603 to 0.694, p = 0.007). MSTS score increased from 12 points after surgery to 23 points six-months after surgery (p<0.001). Conclusions: Endoprosthesis for treatment of MBDf results in low implant failure rate. Patients are satisfied with the functional outcome. QoL is restored six-weeks after surgery. Authors advocate for caution using internal fixation for MBDf due to findings of a possible high early postoperative revision risk.