Relevance. Oral biofilms are integrated three-dimensional symbiontic microbial structures embedded in the extracellular matrix that form not only on the mucous membrane but also on hard surfaces such as enamel and root of teeth, as well as dentures. Our study correlated biofilms and the onset of such a serious oral disease as chronic generalized periodontitis.Material and Methods. The analysis of national and international literature in PubMed, Google Search and eLIBRARY databases over the past 15 years served as material and methods.Results. There is currently an increased interest in studying the mechanisms of microbial biofilms and the factors affecting this process. Planktonic bacteria are more sensitive to antimicrobials than bacteria in biofilms. Several factors, such as gas signalling molecules, may become an important tool for intermicrobial communication in a biofilm. Biofilm microorganisms are highly resistant to antibacterial drugs. Bacteria release enzymes and toxins that stimulate the body to produce large amounts of specific antibodies and cytokines. However, the immune components are blocked by the biofilm extracellular matrix and cannot enter the biofilm. Immune complexes are formed in the infection foci, damage the body's tissues, and aggravate inflammation.Conclusion. Periodontal diseases are the most common oral diseases in humans, and their onset is closely related to the pathogenic properties of the oral microbiota, which exists in biofilms. The mechanisms of biofilm formation are complex and associated with the expression of various microorganism/matrix pathogenicity factors by oral commensal microorganisms. Further study is necessary to understand the way of biofilm formation neutralization and to find an effective treatment for chronic generalized periodontitis.