The aim of the study was to define effectiveness of treating patients with chronic generalized periodontitis with ethidronate sodium and roxythromycin based on clinic and laboratory indices. 32 patients with chronic generalized periodontitis of moderate severity in the acute stage were examined. It was conducted an index assessment of oral health — Green-Vermillion (1964) index of personal hygiene, C.Parma (1960) papillary-marginal-alveolar index, A.Russel (1956) periodontal index. It was determined the depth of periodontal pockets with probing techniques and checking the degree of tooth mobility. In 100 % of cases in periodontal pockets using polymerase chain reaction there were identified various combinations of periodontal pathogens, such as Prevotella intermedia, Tannerella forsythia, Treponema denticola, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis which play a significant role in the development of periodontitis. In patients with chronic generalized periodontitis after the combined treatment with ethidronic acid and roxithromycin there was observed the normalization of clinical and laboratory parameters. These data contribute to the implementation of rational antibiotic therapy tactics.