Abstract: Photodynamic therapy (PDT) is a minimally invasive and promising new modality to combat cancer. The method is based on selective accumulation of sensitizers within tumor cells. The high degree of selectivity offered by this modality has been applied for fluorescent diagnostic of cancer. Photosensitization of a tissue-localized sensitizer generates cytotoxic reactive oxygen species as a result the selective destruction of tumor may be achieved. The PDT's major advantages compared to traditional methods of cancer treatment are better selectivity, low skin and general toxicity. This review highlights first and second generations of sensitizers, their photosensitizing abilities and drawbacks. Future developments in PDT will certainly include the discovery of new photosensitizers and a broadening of the applications of the treatment by various means.