Phase -contrast   microscope was discovered in 1932 by the scientist Frits Zernike who won the Nobel Prize for Physics in 1953 for this scientific discovery. This technique is based on the fact that different parts of living cells have different densities and reflect the light with varying degrees and give different refractive parameters of the light. We used these phenomena to detect Prototheca spp. microalgae which are plant in origin and the wall contains sporopollenin which is biopolymers in nature and not found in animal tissue and this material is not in harmony with the contents of different animal cells. Therefore, it is possible to exploit this scientific phenomenon as a new method for the first time to identify Prototheca spp. microalgae in infected tissues.It has been possible to identify the infected tissue with Prototheca spp. microalgae with phase-contrast microscope as a simple rapid techniques, easy used for unstained slide. Also this technique may help the pathologist to study the life cycle and pathogenesis of this group of pathogen with the other specific  standard methods  for examination.