With the rapid nature of progress in the field of AIDS and HIV, AIDS 2003: A Year in Review provides an essential summary of all major advances during the previous year. The entire field is divided into subspecialties--Virology, Vaccines & Immunology, Clinical Treatment, and Epidemiology and Social Issues. This year's publication features a novel format. Two new sections have been added to complement the state-of-the-art topical review papers, that we have had in years past There is now a 'news' feature and 'best of AIDS' feature. Some of the world's leading researchers and writers look back at the year's research progress and other important matters to provide a coherent synthesis of all our recent work, and its implications for future investigations. AIDS 2003: A Year in Review will be cited in Index Medicus/Medline, Current Contents (Life Sciences), Science Citation Index, and Excerpta Medica.