In addition to the tasks of pre-digestion, buffering of food acids, protection and remineralisation of tooth substance and moistening of the oral mucosa, saliva also plays an important role in wound healing, and a reduced flow rate represents a serious problem for patients. The saliva flow rate measurement (sialometry) on patients before radiation therapy should take place as a routine procedure, the costs are covered by the statutory health insurance. Due to the increased risk of caries in patients with reduced salivary flow, optimum oral hygiene and professional prophylactic care are crucial. In addition to nutritional guidance of the patient, saliva substitutes and medicinal salivary stimulants are available on the market. Saliva analysis has recently become more of public interest, especially in the field of personalized medicine as various drugs, viruses and DNA can be detected in saliva.