The use of positron emission tomography (PET) in clinical oncology continues to increase and although there is now a large literature on the use of PET with various tracers in a wide variety of cancers, there has previously been relatively little use specifically in the evaluation of skeletal metastases. However, a number of reports on PET in this area of oncology are now becoming available. The potential advantages of PET over conventional nuclear medicine techniques, including improved spatial resolution, absolute quantitation and the acquisition of tomographic studies as a routine, are also of potential benefit in this area. The bone agent, 18F-fluoride and the tumour agent 18F-fluorodeoxyglucose, have been used to evaluate both benign and malignant skeletal disorders qualitatively and quantitatively and the current knowledge with respect to the skeleton in cancer patients is summarised in this article.