We evaluated functional outcomes for patients who underwent surgery for resection and endoprosthesis replacement for primary tumours around the knee. We used the Musculoskeletal Tumour Society Scoring System (MSTS) for functional evaluations to compare differences between distal femur (DF) and proximal tibia (PT) placements. The study sample included 34 cases of distal femur and 20 cases of proximal tibia endoprosthesis replacement. Primary tumours were classified as follows: 33 osteosarcoma, 20 stage III giant cell tumour (GCT) and one case of mesenchymal chondrosarcoma. The mean MSTS score for both DF and PT endoprosthesis together was 21.13 (70.43%), and The MSTS scores for DF was 21.94 (73.13%) and PT was 19.75 (65.83%) Infection developed in 7 cases and 5 of which were PT endoprosthesis cases. Three deep infections required early, two-stage revision and resulted in poor MSTS scores. We conclude that endoprosthesis replacement for primary bone tumours had early good to excellent functional outcome. There were no differences in functional outcomes when comparing distal femur endoprostheses with proximal tibia endoprostheses.