Multi-modality imaging is rapidly becoming an essential tool in oncology. Clinically, the best example of multimodality imaging is seen in the rapid evolution of hybrid positron emission tomography (PET)/computed tomography (CT) and single positron emission computed tomography (SPECT)/CT scanners. However, use of multi-modality imaging is prone to artefacts and pitfalls. Important artefacts that may lead to clinical misinterpretation result from the use of CT data to correct for attenuation and the existence of mismatches between the fused images, for example due to respiratory movement. Furthermore, for institutions who proceed from a standalone PET to a hybrid PET-CT, there is an issue of interchangeability between these systems, especially for quantitative studies. Another issue is visualisation: hospital PACS is not sufficiently capable of adequately viewing integrated images. This article reviews and illustrates the most common artefacts and pitfalls that can be encountered in multi-modality nuclear medicine imaging. For correct management of oncological patients it is essential to be able to detect and correctly interpret these artefacts and pitfalls. Therefore, solutions and recommendations to these problems are provided.