In the course of preparation of aqueous solutions of the polyene antibiotic levorin, the latter is recovered in the solid phase forming granular submicroscopic structures. If the cells of Candida guilliermondii are treated with submicroscopic granular structures (SMGS) of levorin, the structures are adsorbed on the surface of the yeast cell walls. Some visible changes occur in the ultrastructure of the yeast cells incubated with SMGS of levorin for 5 min: the inner layer of the cell wall becomes loose, the periplasmic space appears, the cytoplasmic membrane becomes thicker, the mitochondria swell, and fragmentation of the mitochondrial cristae takes place. Dense round alien bodies 20--40 mn in size can be discerned in the periplasmic space of such cells. If the yeast cells are treated with the levorin structures for a longer period of time (15--60 min), the cell ultrastructure is entirely disorganized.