The authors present the first study of the efficacy of electromagnetic radiation on the frequency of nitric oxide absorption and emission molecular spectrum in treatment of periodontitis. The use of the method resulted in certain clinical improvements (reduction in gum mucosal edema and hyperemia) and betterments in patients' sensations (pain and discomfort reduction). The cytokine profile (the ratio of pro- and anti-inflammatory cytokines: TNF-a, IL-8, IL-4) and the index of secretory A immunoglobulin normalized, which evidenced the efficacy of the therapy. An optimal regimen of the application of the method was developed.