Saliva exerts multiple functions in relation to the initial digestive processes taking place in the upper parts of the gastrointestinal tract. Ingestion of food and beverages, in turn, is a strong stimulus for secretion of saliva with a differential composition depending on the neuronal stimulation pattern. This review paper provides insight into the mechanisms by which saliva acts in relation to taste, mastication, bolus formation, enzymatic digestion, and swallowing. Also the protective functions of saliva including maintenance of dental and mucosal integrity will be discussed as they indirectly influence the digestive process. The final part of this paper focuses on the implications of xerostomia and salivary gland dysfunction on gastrointestinal functions. This article is protected by copyright. All rights reserved.