Photodynamic therapy is treatment modality involving the administration of photosensitizing compound, which selectively accumulates in the hyperproliferative target cells followed by local irradiation with visible light of lesion. Eventually target tissue will be damaged by necrosis and apoptosis. Action of treatment is described from absorption of light till damage of tissue. Several rationale proposals to increase the efficiency of described treatment modality are suggested: to evaluate the antiproliferative activity of new coming photosensitizers, to combine photosensitization with other treatment modalities in molecular level, exploring mechanism of apoptosis, to increase the efficiency of treatment by combination with ionizing radiation, hyperthermia or ligation of peripheral benzodiazepine receptors.