Saliva contains several types of antimicrobial peptides that play a role in innate immunity. Peptides that were recently added to this list are the defensins. The purpose of this review is to summarize what is known about the production and role of defensins in the salivary glands and to discuss their therapeutic potential. The Alpha-defensins, human neutrophil defensins (HNP)-1, -2, and -3, have been detected in saliva and may be derived from neutrophils. The Beta-defensins, human Beta-defensins (HBD)-1 and -2, have also been detected in saliva. Although it has been speculated that salivary HBDs are derived from keratinocytes that line the oral mucosa rather than from the salivary glands, the HBD-1 peptide was recently found to be specifically expressed in salivary ductal cells, although not in acini. Defensins may be useful for the treatment of periodontal disease and for the prevention of caries and periodontitis.