Radiographic evaluation is an extremely powerful tool that allows the orthopaedic surgeon to characterize and classify bone lesions by their appearance and by the reaction of the surrounding bone and soft tissue. Careful and analytical characterization of bone lesions on plain radiographs often enables the surgeon to greatly narrow the differential diagnosis. The goal of this exhibit is to provide the reader with a fundamental algorithm for the radiographic evaluation of benign and malignant bone lesions. The algorithm is summarized in the flow charts in Figures 1 and 2, which provide a step-by-step process for the classification of lesions. Also shown in the charts are important examples of each category.