OBJECTIVE: The goal of this study was to correlate tympanic membrane (TM) and middle ear (ME) pathologies in mucoid otitis media (MOM). METHODS AND MATERIAL: Forty ears with MOM and 56 control ears were retrospectively evaluated for TM and ME pathologies. Comparisons of TM thicknesses in MOM versus control ears were correlated with the Student t test; χ2 analysis was used to correlate pathologic findings of the TM and ME. RESULTS: Thicknesses in all quadrants except the umbo were increased in MOM because of infiltration of inflammatory cells and fibrosis. The most common ME pathologies were granulation tissue and fibrosis. Significant correlations included (1) TM retraction and ME granulation tissue and fibrosis and (2) pars fiaccida, posterosuperior, and anteroinferior thickness and ME granulation tissue and fibrosis. CONCLUSION: TM changes are likely to occur in patients with otitis media with effusion (MOM), and their presence is a strong indication of underlying ME pathology.