Radiological error is inevitable and usually multifactorial. Error can be secondary to radiologist specific causes, including cognitive and perceptive errors or ambiguity of report, or system related causes, including inadequate, misleading or incorrect clinical information, poor imaging technique, excessive workload and poor working conditions.In this paper, we discuss a systematic approach to reduce errors in oncological radiology reporting, thus reducing risk to the patient. Rather than attempt to discuss all types of error we concentrate on the most important and commonly occurring errors that we have encountered over 20 years of practice, based on a weekly discrepancy reviews of our practice and independent reviews of clinical and research imaging from other institutions. This review focuses on CT scan reporting for staging, surveillance and response assessment of cancer patients, but the messages apply to all imaging modalities.