OBJECTIVES: To assess the following themes among referring physicians: A. Importance of acquiring information about previous diagnostic exposures; B. Knowledge about radiation doses involved, familiarity with radiation units and, age related radiosensitivity; C. Opinion on whether patients should be provided information about radiation dose; and, D. Self-assessment of appropriateness of referrals. DESIGN: A prospective survey using a web based questionnaire. SETTING: International survey among referring physicians. PARTICIPANTS: Referring physicians from 28 countries. MAIN OUTCOME MEASURES: Knowledge, opinion and practice of the four themes of the survey. RESULTS: 728 responses from 28 countries (52.3% from developed and 47.7% from developing countries) indicated that while the vast majority (71.7%) of physicians feel that being aware of previous history of CT scans would always or mostly lead them to a better decision on referring patients for CT scans, only 43.4% often enquire about it. The majority of referring physicians (60.5%) stated that having a system that provides quick information about patient exposure history would be useful. The knowledge about radiation doses involved is poor, as only one-third (34.7%) of respondents chose the correct option of the number of chest x-rays with equivalence of a CT scan. 70.9% of physicians stated that they do not feel uncomfortable when patients ask about radiation risk from CT scans they prescribe. Most physicians (85.6%) assessed that they have rarely prescribed CT scans of no clinical use in patient management. CONCLUSIONS: This first ever multi-national survey among referring physicians from 28 countries indicates support for a system that provides radiation exposure history of the patient, demonstrates poor knowledge about radiation doses, supports radiation risk communication with patients and, mandatory provisions for justification of a CT examination.