Clinical application of photodynamic therapy (PDT) and fluorescence diagnosis is being extend-ed in Russia. A. Tsyb MRRC scientists headed by Professor M. Kaplan have conducted experi-mental studies of the photosensitizers (PS): Photochem, Photosens, Photolon, Photoditazin, Radachlorin, Photoran, belonged to different classes, estimated their therapeutic effectiveness for malignant tumors of different histologic type. From the study of basic mechanisms of photo-chemical reactions with chlorine photosensitizers it became evident that the photosensitizers de-stroyed microciculatory bed, inhibited proliferation and tumor cells functional activity, induced apoptosis and necrosis at early stages of a tumor development. Effects of PS dosage and dose of light to be delivered to a target on a treatment outcome were studied. The results of experi-mental studies were used to support clinical application of focal, interstitial, systemic techniques with different PS as individual treatment modalities or as a modality combined with radiation therapy, surgery, chemotherapy, electrochemical lysis. Optimal PS and light exposure doses were determined, indications for the use of optimal PS and light doses for treatment of malignant neoplasms of the skin and the mucous membranes were formulated. Due to the use of high-tech effective treatment modalities developed in the Department of Fluorescence Diagnosis and Pho-todynamic Therapy of A. Tsyb Medical Radiological Research Centre – the branch of the Medical Research Radiological Centre thousands of patients have been cured.