Appendicular osteosarcoma represents the commonest malignant bone tumour for which limb salvage surgery and endoprosthetic replacement is performed. These techniques have been made possible due to the introduction of effective neoadjuvant chemotherapy and demand a high degree of accuracy in the assessment of local staging. This is now achieved with a combination of imaging techniques, the most important of which is magnetic resonance imaging (MRI). For the purposes of local staging, it is useful to divide disease extent into intramedullary and extramedullary. Intramedullary extension includes an assessment of longitudinal medullary extent, epiphyseal involvement and skip metastases. These factors will determine the site of bone resection. Extramedullary extension includes an assessment of joint involvement, relationship to the neurovascular bundle and involvement of muscle compartments. These factors will determine the feasibility and type of limb salvage performed. This article reviews the accuracy of imaging in the local staging of appendicular osteosarcoma.