Receipt of multiple vaccines over a brief time is a common feature of military overseas deployments. Although recent studies have shown that the anthrax vaccine is highly reactogenic, there is no clear evidence from Gulf War studies that link the anthrax vaccine to Gulf War illness. Taken together, limited results from Gulf War epidemiologic studies, the preferred administration of the vaccine to troops in support locations, and the lack of widespread, multi-symptom illness resulting from current deployments, all combine to indicate that the anthrax vaccine is not a likely cause of Gulf War illness for most ill veterans. However, limited evidence from animal research and Gulf War epidemiologic studies indicate that a link between Gulf War illness and receipt of a large number of vaccines cannot be ruled out.