The aim of the study was to determine whether clinical information alters the CT report. This prospective blinded study consisted of 50 consecutive patients who attended a Department of Radiology for CT. Each study was interpreted by two of three consultant radiologists, before and after knowledge of the clinical information. 19 reports were changed after clinical information was known. Clinical follow-up was available in 15 cases. In ten cases the reports were more accurate after clinical information and in five cases the reports were less accurate. In three of the five cases where accuracy was reduced, the clinical information was incorrect. It was concluded that clinical information affects the CT report. If the information is accurate it has a beneficial effect; if it is inaccurate it has a detrimental effect. The more complex the investigation, the more important the clinical information. There was a correlation between readers regarding the influence of clinical information. Correct clinical information therefore improves the radiology report. It is the responsibility of the clinician to provide this information in an accurate and legible form.