Positron emission tomography (PET) has become a very useful adjunct to anatomic imaging techniques, because it can provide an in vivo method for quantifying functional metabolism in normal and diseased tissues. Clinical trials with [(18)F] 2-deoxy-2-fluoro-D-glucose (FDG), the most commonly used radiolabeled tracer for PET imaging, has demonstrated increased accumulation of FDG in cancer tissue. FDG-PET is now widely used for the detection, differentiation, grading, staging, and monitoring of various neoplasms. However, the significance of FDG-PET in such evaluations of primary bone tumors and tumor-like lesions has not been extensively elucidated. In this article, we present recent advances in FDG-PET studies for evaluating primary bone tumors and tumor-like lesions.