Writing a Clinical Evaluation Report (CER) is a complex task. Throughout the process, manufacturers frequently discover that there are more documents and further analysis that they should have prepared. These tasks include fully defining the intended purpose of the device, completing thorough systematic reviews of both the scientific literature for ‘state of the art’ research and ‘pivotal’ (device specific) research as well as comprehensive vigilance database searches. To make life easier, we have created a short list of five essential principles to consider before starting a CER.