The clinical examination of 36 tobacco smokers with chronic generalized periodontitis of light, average and severe degree was carried out. The examination established poor hygienic condition of oral cavity, less expressed inflammatory reaction of tissues of periodont and predominance of occurrences of destruction of alveolar portion of bone as compared with the group of 59 non-smoking patients with chronic generalized periodontitis of light, average and severe degree. The study demonstrated higher rate of detection of T. forsythia in smokers as compared with non-smoking patients at all stages of of development of chronic generalized periodontitis. Under light stage of chronic generalized periodontitis increasing of rate of detection of T. forsythia more than twice was registered. P. gigngivalis and P. intermedia were detected in smoking patients with light stage of chronic generalized periodontitis either in the same values or more rarefy as compared with non-smokers. In the group of smokers with average stage of chronic generalized periodontitis increasing of rate of occurrence of association of T. forsythia-P. gigngtvalis-P. intermedia occurred more than five times in comparison with non-smokers. The obtained results indicate on relationship between alterations ofmicrobiota and aggressive development of chronic generalized periodontitis in smoking patients and on development in periodontal recesses of smokers of favorable conditions for growth of T. forsythia. The presence of T. forsythia is a significant factor of development of destructive processes in tissues of Periodont.