Photodynamic therapy (PDT) of cancer is an advanced application of gold nanostructures. The purpose of the research is to study the morphological changes in the transplanted sarcoma S45 at PDT using nanocomposites based on gold nanorods (GNRs). GNRs synthesized with the germ method and covered by a silicon coating, functionalized by hematoporphyrin, were intratumorally injected in rats with transplanted sarcoma S45. The tumor was irradiated by He-Ne laser with a wavelength of 632.8 nm.