Periodontal therapy is still based on elimination of plaque and calculus by mechanical means. Phase I therapy and periodontal surgical methods remain the main stay for elimination and control of periodontal disease. Antimicrobial therapy is also used in cases of aggressive periodontitis, necrotizing ulcerative periodontitis and in cases of pericoronitis. However, many patients always hope to gain control over their periodontal disease with non-surgical means itself. One of the innovative and novel way of periodontal therapy is the use of photodynamic therapy (PDT). Photodynamic therapy (PDT) can be defined as eradication of target cells by reactive oxygen species produced by means of a photosensitizing compound and light of an appropriate wavelength. The application of photosensitizing dyes and their excitation by visible light enables effective killing of periodontopathogens. PDT application has an adjunctive benefit besides mechanical treatment at sites with difficult access. Necessity for flap operations may be reduced, patient comfort may increase and treatment time would decrease. Schlagwörter: photodynamic therapy, periodontitis, photosensitizing dyes