Introduction. Our understanding of photodynamic therapy (PDT) is crucial for the applications of this treatment. In this physical phenomenon occurs light absorption by the applied photosensitizer, which results in its excitation to higher electron levels. After activation, a series of complex physicochemical processes take place in the tissues, Aim. The aim of this study was to describe the basic naturally occurring photosensitizers used in PDT techniques. This study clarified applications of photosensitizers. Material and methods. This study was used basic information about PDT reaction and the selective destruction of the tumor by photooxidation: a photosensitizer, a light source and oxygen. The papers reviewed here are based on Medline/Pub. Analysis of the literature. Photodynamic therapy is an innovative form of treatment. This method is not a commonly used therapeutic and therapeutic tool, but a supplement to many already tested and analyzed techniques. Thanks to continuous research, this method has a wider and wider range of applications in medicine. Conclusion. The data indicates increased number of papers regarding applications of PDT in medicine.