Sažetak Biological non-specific defence factors which are mainly found in the saliva are discussed in the introduction. Emphasis is placed on the fact that it is indispensable to observe separately the secretion of the salivary glands and the effect of bacteria which form the flora of the oral cavity, if a correct assessment is to be made of the immunological significance of the numerous regulative factors. Essential factors are listed to which anti-bacterial effect in the saliva is ascribed. The following are mentioned: the concentration of hydrogen ions, salts and osmotic relations and the effect of ferments through ions. A survey is given of the leukocytes and the leukocytal substances which are among the regulative factors of local immunity in the oral cavity. Phagocytosis is mentioned and the origin of leukocytes in the oral cavity. The opinion of different authors is reviewed on ferments and other humoral substances equally serving as regulative factors of the flora in the oral cavity. The most im portant factors mentioned are: superficial phagocytosis, the effect of lysozymes, lipase, mucin, inhibin and mutin. Concluding emphasis is placed on the fact that the above mentioned factors are responsible for the maintenance of the specific structure of the oral flora. Numerical restriction of the flora in the oral cavity is quite well handled by mechanical means such as continuous exfoliation of the epithelial cells in the oral cavity, while elim ination of the flora is carried out by food and self cleaning.