The chapter discusses about the saliva, which is the fluid released into the oral cavity by salivary glands and is the result of both secretion and excretion. Saliva helps in formation of bolus by moistening solid food; moistens and protects epithelium and teeth; flushes and cleans oral cavity; and helps in speech by moistening epithelial surface. The amount of saliva secreted varies from person to person, depending on type of food taken, age, degree of mechanical stimulation, emotional condition, etc. On an average, 1500 mL is secreted per day under normal condition. Salivation is controlled exclusively by nervous system. The salivary glands are richly supplied with both sympathetic and parasympathetic nerves. The mucin and water contents of saliva act as lubricant during mastication, formation of bolus of food and swallowing as well as in sensation of taste. The only important digestive enzyme present in the saliva is ptyalin or salivary amylase. A large number of microorganisms are present in the saliva which contributes to its antibacterial effect. Saliva is a route of excretion also, by which certain substances are excreted. When freshly shed blood is diluted with saliva, its clotting time is reduced. Mucin and microorganism from saliva are the main factors responsible for the formation of plaque, which leads to caries and calculus formation.