Objective: To study the cellular characteristics of Reissner's membrane (RM) in temporal bones (TBs) from patients with endolymphatic hydrops with symptoms of Meniere's disease (EH/+MD) and TBs with endolymphatic hydrops without symptoms of Meniere's disease (EH/-MD) in an effort to understand the role of endolymphatic hydrops in MD symptoms. Study Design: Comparative study of human TB histopathology. Methods and Materials: Epithelial and mesothelial cellularity of RM from control TBs, TBs from patients with EH/+MD, and TBs from patients with EH/-MD were compared. The cellularity of epithelial and mesothelial cell nuclei (defined as number of cells/100 μm width of RM) were counted along the width of RM. The width of RM was measured from the vestibular crest of the spiral ligament to the limbus spiralis. Results: The cellular densities of epithelial cells in the basal and middle turns of RM were significantly higher in the EH/+MD and EH/-MD groups compared with "controls." There was no difference in epithelial cellularity between EH/+MD and EH/ -MD. There was a decrease in the number of mesothelial cells of RM in the basal turn in EH/+MD and EH/-MD groups (statistically significant only in EH/+MD group) when compared with controls. The number of mesothelial cells of RM in the middle turn in EH/+MD and EH/-MD groups were significantly decreased compared with normals. Discussion: Similar findings in cellularity of RM in temporal bones with EH/+MD and EH/-MD suggest that pathophysiologic mechanisms other than hydrops may be responsible for symptoms in Meniere's disease.