Antimicrobe.org (http://www.antimicrobe.org) is a World Wide Web-based version of the textbook Antimicrobial Therapy and Vaccines, volumes I and II. The Web site currently consists of 3 texts (Microbes, Antimicrobial Agents, and HIV Clinical Manual) and will soon include a fourth, Empiric. The Web site focuses on therapy for infectious diseases, and it covers, in comprehensive detail, a great majority of infections encountered today. The dynamic nature of a Web-based reference allows for information to be frequently updated and enhances a physician's searching capabilities to find answers to very specific clinical questions and the latest available evidence. A Smart Search engine allows users to ask specific questions and to find focused answers, either within the textbook or through PubMed via a guided PubMed references option. The Web site also provides clinical vignettes and minireviews on hot topics in infectious diseases and hyperlinks to other important articles or Web sites. Chapters are written by experts in their field who provide evidence-based information, as well as anecdotal reports about rare infections. Antimicrobe.org would be of great benefit to physicians who treat infections on a routine basis.