The secretions of the major and minor salivary glands, together with the gingival crevicular fluid, constitute the oral fluid or whole saliva which provides the chemical milieu of the teeth and oral soft tissues. The crucial role of saliva in the maintenance of dental health is demonstrated by the morbidity associated with loss of salivary gland function. In this article, the physiology of the secretory process, the reflex control of whole saliva flow rate, the composition of the fluid, the factors affecting its composition, and the functions of the organic and inorganic components are described. Finally, the clinical aspects of salivary gland dysfunction are briefly discussed.