This study examined the relationship between objective changes in electrocochleographic (ECochG) parameters and subjective changes in symptoms in a group of patients with Meniere's disease/endolymphatic hydrops (MD/ELH) after application of positive and negative atmospheric pressure changes to the sealed ear canal. Our goals were to further examine the therapeutic effects of atmospheric pressure change on the treatment of MD/ELH, as reported by a series of Swedish studies, and to examine the utility of ECochG for monitoring these effects. By combining a clinical immittance unit and an evoked potential unit, ECochG responses were obtained from the tympanic membrane while different atmospheric pressures were applied indirectly to the middle ear via the external ear canal. For comparison, ECochG responses at various atmospheric pressures also were obtained for otologically normal subjects. For the MD/ELH group, there was a significant (p<0.01) reduction in the abnormal summating potential/action potential (SP/AP) amplitude ratio, although the amplitude ratios did not become “normal.” There was no significant effect of ear canal pressure change on ECochG components for the normative subjects. Although these findings were encouraging regarding the therapeutic effects of overpressure, they were not accompanied with changes in MD/ELH symptoms.