Volume 28 in the series of Side Effects of Drugs Annuals continues to serve its primary goal: to provide clinicians and medical investigators with a reliable and critical yearly survey of new data and trends in the area of Adverse Drug Reactions and Interactions. An international team of specialists has reviewed new data and trends by selecting from the year's writing all that is truly new and informative, by critically interpreting it, and by pointing to whatever is unproven or misleading. The use of the book is enhanced by separate indexes, allowing the reader to access the text via drug name, adverse effect, or drug interaction. The current annual includes an essay by the editor, Dr Jeffrey Aronson, entitled 'Classifying Drug Adverse Reactions in the 21st Century.' In it he describes how the modern approach to classifying adverse drug reactions takes into account the dose that causes the reaction, the time-course of the reaction, and the susceptibility factors that increase the individual patient's risk, and shows how this analysis can facilitate regulatory decision making.