OBJECTIVES: This study evaluated several aspects of patients' and providers' knowledge and attitude regarding emergency CT scan use. Specifically, is patient awareness of radiation risks changing over time and do levels of education affect this knowledge? Meanwhile, do emergency medicine providers discuss risks with patients and do patients want to know about these risks? METHODS: We conducted a survey of clinically stable patients in the emergency department (ED) after undergoing a CT scan. RESULTS: 200 patients were surveyed. 82 (41%) were aware that CT scans are associated with radiation exposure. 50 (25%) patients were aware that radiation from CT can increase overall lifetime risk of cancer compared with only 2/76 (3%) conducted in 2002. 29 (14.5%) providers specifically discussed radiation risk with patients prior to the CT. There was a significant trend towards knowledge that CT uses x-rays among those with more education. However, there was no association between level of education and knowledge of cancer risk associated with radiation risk from CT. 82 (41%) would have liked more information regarding radiation risks from the provider. CONCLUSIONS: ED patient knowledge has increased significantly over the past 8 years. At the same time, there is a trend towards ED providers more commonly discussing these risks. Level of education is associated with knowledge that CT uses x-rays, but not with knowledge that this is associated with a greater risk of cancer. Patients often want to be informed of these risks.