With the light microscope, hyaline bodies of Rushton may appear lamellar or granular. In this investigation, the ultrastructures of both lamellar and granular forms were studied in formalin fixed material, and in specimens fixed in osmium tetroxide. The lamellar type was composed of alternating electron dense and electron lucent layers, the outermost layer always being electron dense. The granular type was composed of amorphous material in which fragments of red blood cells could be seen. Some hyaline bodies were partly granular and partly lamellar. The surfaces of the epithelial cells apposed to both types showed large numbers of hemidesmosomes, but no basal lamina was seen. The amorphous material in the granular hyaline bodies appeared very similar to the substance of the degenerating red blood cells, and extravasated red cells were commonly found in the adjacent connective tissue. The results suggest that the granular type is formed from degenerating red blood cells, and that the lamellar pattern may result from segregation of components within the mass rather than by an incremental form of growth. No support was found for the hypotheses that hyaline bodies are keratinous or a secretory product of the epithelial cells.