Photoelectron diffraction is proposed to determine nondestructively the polarity of wurtzite crystals with polar surfaces (c-plane). Small segments of polar plots of photoemission from anion core levels in the azimuthal plane are qualitatively different for two polarities around the polar angle 20°. The magnitude of the ratio of electron photoemission intensities at two polar angles I20/I23 can be utilized as a simple criterion determining the crystal polarity.