Iodine deficiency, especially mild deficiency, is still a widespread problem in the WHO European Region. Since the last WHO report on iodine deficiency in the Region was published 15 years ago, a wealth of new data on iodine status has become available, particularly concerning vulnerable population groups. This report reviews the iodine status in the WHO European Region, as well as current scientific knowledge on the consequences of mild iodine deficiency, dietary sources of iodine and the present effectiveness of iodine deficiency prevention measures. This report is also unique as it combines information sourced not only from scientific publications and public health reports, but also animal husbandry science and reporting, and the food industry.