The doses of radiation from computed tomography (CT) are relatively high, yet CT is being increasingly utilized. Furthermore, the radiation-induced lifetime risk of cancer mortality is higher at younger age. The purpose of this study was to find out whether previous CT examinations done on patients aged under 35 years were justified, and if not, whether there would have been other, more justifiable imaging modalities available. Fifty CT examinations of the head and 30 CT examinations each of the lumbar spine, cervical spine, abdomen, nasal sinuses and trauma were evaluated consecutively since the beginning of the year 2005 by using electronic patient files, the referral guidelines for imaging recommended by the European Commission and certain principles of classification. Seventy-seven per cent of the CT examinations of the lumbar spine, 36% of the head, 37% of the abdomen, 20% of the nasal sinuses and 3% of the cervical spine were unjustified. Most of these unjustified examinations could have been replaced by magnetic resonance imaging. In order to reduce utilization of ionizing radiation, both the referring practitioner and the radiologist responsible for the examination should carefully consider the justification for CT examinations and the possibility of using other imaging modalities.