Photodynamic therapy (PDT) is gaining in importance as an alternative treatment procedure for lesions of the oral cavity. The desired goal is an effective and easily controllable therapy with the most possible homogeneous irradiation of the oral cavity lesions. The oral cavity is characterised by complex geometry which must be considered with the selection of the applicators and the appropriate dosimetry. Using MS Excel, functional tables were formulated illustrating standardized geometrical conditions. With the assistance of these tables, the irradiation surface and the appropriate energy or power density can be determined for each application. The applicators used were isotropic of different length (Coherent) - cylindrical and hemizylindrische application systems 2-4cm long and Microlens fibers (Coherent). Power Densities of fewer than 250mW/cm2 were used in order to avoid thermal effects of the oral mucous membrane. Aphthen were treated with a dose of 40-80 J/cm2 and Leukoplakien or Lichen Planus with a dose of 80-130 J/cm2. The use of interactive tables enables a standardisation of the irradiation parameters - even those with different geometrical proportions. In light dosimetry there are differences in the handling of different lesions of the oral mucosa depending upon indication and used applicator. With the appropriate applicator it is possible to implement an even light dose and in the rear areas of the oral cavity. With the help of interactive tables introduced by us, an optimized and standardized treatment protocol can be achieved. Keywords: Lichtdosimetrie, Photodynamische Therapie