During the past decade the clinical value of PET imaging has been investigated for many different tumors. As knowledge of the advantages and limitations of this modality increased, PET has gained acceptance in tumor imaging. (18)F-FDG PET is now successfully used and approved for procedure reimbursement in many types of cancer-for example, lung cancer, melanoma, lymphoma, head and neck tumors, brain tumors, esophageal cancer, and colorectal cancer. In osteosarcoma, the introduction of neoadjuvant chemotherapy has dramatically improved survival rates, thus changing the demands for state-of-the-art imaging to provide detailed information on tumor staging and grading, evaluating treatment, and detecting recurrences. In this review, the available literature on PET imaging in osteosarcoma patients is critically summarized with respect to diagnosis, staging, therapy monitoring, and follow-up focusing on the clinically used tracers (18)F-FDG and (18)F-fluoride ion. Potential and probable indications are outlined. Because of the relatively small number of patients enrolled in clinical trials published to date, further research needs to be done in larger, prospective patient series to determine the full utility of PET in osteosarcoma.