Introduction. Historically, amputation or rotationplasty were the treatment of choice in skeletally immature patients. The introduction of expandable endoprostheses in the late 1980s offered the advantages of limb-salvage and limb length equality at skeletal maturity and a promising alternative with improved cosmetic results and immediate weight bearing. Objective. to describe the Rizzoli experience in reconstruction with three different types of expandable prostheses in growing children with malignant bone tumors of the femur, assess the outcome of limb salvage in these patients, analyze survival and complications related to these prostheses used over time. Materials and Methods. Between 1996 and 2010, 39 expandable implants were used in 32 children (16 boys and 16 girls; mean age, 9 years at initial surgery) with bone sarcomas of the femur treated with limb salvage using expandable prostheses. The most common diagnosis was osteoblastic osteosarcoma; all children were classified as having a stage IIB lesion and had preoperative and postoperative chemotherapy. The minimally invasive Kotz Growing prosthesis was used in 17 cases (10 primary implant and 7 revision after failure of non-invasive Repiphysis®), the non-invasive Repiphysis® in 15 cases and Stanmore® expandable prostheses in 7 cases. The mean follow-up was 48 months. Functional evaluation and survival analysis of the children and implants were performed. Results. The rate of implant-related complications was 51.3%; 9 prostheses (23%) were revised because of aseptic loosening, infection and breakage. The mean total lengthening was 26 mm (4 to 165 mm) achieved by 78 procedures (2.4 procedures/patient). Three of the nine children who reached skeletal maturity had limb length equality and six discrepancy of 15–30 mm. The survival of the children was 94% and 76% at 24 and 72 months. The survival of the primary prostheses was 90% and 70% at 24 and 72 months. Survival was significantly higher only for the Kotz compared to the Repiphysis® prostheses (p= 0.026). The mean MSTS score was excellent (79%) without a significant difference between the type of prostheses (p= 0.934). Conclusions. In the growing children expandable prostheses are viable reconstruction options with good and excellent oncological and functional outcome, and limb-length equality at skeletal maturity. Mechanical failures including aseptic loosening and breakage, dysfunction of the expansion mechanism, contractures especially around the knee, dislocation and infection were the most common; some designs have been associated with an unacceptably high inherent risk of complications. However, the non-invasive systems are associated with high complications and failure rates. Early experience is promising, but further study is warranted to determine long-term structural integrity of these newer designs