OBJECTIVE To assess the annual per caput and collective effective dose to the United Kingdom population from medical and dental X-ray examinations. METHODS The results of a detailed survey of the frequency of X-ray examinations during the financial year 1997/1998 were combined with contemporary data on the effective doses typically received by patients. The resulting per caput and collective dose for 1997/1998 was updated to 2001/2002 by using annual statistics on the total numbers of computed tomography (CT), interventional and conventional examinations collected by the English Department of Health. RESULTS The annual per caput effective dose for the UK in 2001/2002 was estimated at 0.38 mSv. Over the last 10 years CT has more than doubled its contribution and is now responsible for 47% of the collective dose from medical X-rays. The contribution from conventional radiographic and fluoroscopic examinations has nearly halved to about 34%. Interventional and angiographic procedures together contribute the remaining 19%. CONCLUSIONS The annual per caput effective dose of 0.38 mSv is low in comparison with other countries having similarly developed systems of health-care. This is due to both a lower frequency of X-ray examinations per head of population and generally lower doses in the UK than in other developed countries.