Recent events have drawn attention to cases of inhalational and cutaneous anthrax associated with contaminated mail. Gastrointestinal anthrax, the disease caused by ingestion of Bacillus anthracis organisms, has rarely been reported in the United States. This review provides background information on the gastrointestinal form of the disease. We describe the clinical course of gastrointestinal anthrax, outline current therapy, review the microbiology of B anthracis, examine the epidemiology of natural outbreaks, discuss considerations regarding deliberate contamination, and summarize existing literature on the inactivation of spores present in food and water.