Evidence-based guidelines for the management of patients with blastomycosis were prepared by an Expert Panel of the Infectious Diseases Society of America. These updated guidelines replace the previous management guidelines published in the April 2000 issue of Clinical Infectious Diseases. The guidelines are intended for use by health care providers who care for patients who have blastomycosis. Since 2000, several new antifungal agents have become available, and blastomycosis has been noted more frequently among immunosuppressed patients. New information, based on publications between 2000 and 2006, is incorporated in this guideline document, and recommendations for treating children with blastomycosis have been noted.