Introduction. The diseases of the marginal periodontium are among the first places in periodontal diseases. The timely detection of these diseases requires imperative implementation of some effective and contemporary diagnostic methods and the choice of an appropriate treatment tactics to prevent relapses.  Aim of study. To make an efficient diagnosis of localized chronic catarrhal gingivitis, mild form and to select the optimal methods of treatment.  Materials and methods. The study included 20 patients with the diagnosis of localized chronic catarrhal gingivitis, mild form. The average age of the patients enrolled in the study was 18-35 years. The patients were subjected to the following methods of investigation: orthopantomogram, bleeding indices test, and determination of soft dental deposits.  The diagnosis-based treatment tactics was: removal of tartar, professional brushing and applications with antiseptics and antimicrobials.  Results. Most patients were identified during dental care-routine check-ups. After the treatment, the gum bleeding was ceased and the inflammatory process was stopped. Professional cleaning of affected areas was performed and follow-up control over the dental tartar formation was done. Conclusions. The asymptomatic evolution of the initial stages of inflammatory gum diseases leads to late dental check-ups and professional dental care.