Positron emission tomography (PET) has become an integral part of the management of patients with cancer as well as some cardiac and neurological diseases. 18F-fluorodeoxyglucose (FDG) PET is commonly used to stage cancer patients after initial diagnosis, but is increasingly used at other points in the patient's management, including the assessment of treatment response and detecting recurrent disease. In common with most imaging techniques there are pitfalls in interpretation of PET and PET/computed tomography (CT) studies. Many potential pitfalls and artefacts have previously been described with 18F-FDG PET imaging, but more continue to become apparent as worldwide experience increases. In addition, the advent of combined PET/CT scanners in clinical imaging practice has brought its own specific pitfalls and artefacts. A knowledge of the normal distribution of FDG and its physiological variation is essential before interpreting PET scans as well as an awareness of the potential false positive and negative cases that can occur. It is important that referring clinicians, PET/CT interpreters and imaging technologists/radiographers are aware of potential pitfalls so that their impact is minimised and that the image data are acquired and interpreted in the most accurate manner. With careful patient preparation, attention to detail and adequate training, the se artefacts and pitfalls may be minimised allowing this powerful hybrid imaging technique to realise it's potential. This paper attempts to describe some of the common pitfalls and artefacts and how they can be avoided or appropriately interpreted.