The transtympanic electrocochleography was performed in the clinically defined Meniere's disease group and normal control group to evaluate significance of the summating potential/action potential amplitude ratio(SP/AP). And abnormal SP/AP ratio was compared to results of the intravenous glycerol test in the Meniere's group. The mean of the SP/AP ratio was significantly different between 2 groups, with 0.263 in the normal group and 0.462 in the Meniere's group. The ratio was efficient diagnostic measure of Meniere's diseases with 70.3% and 95.2% in sensitivity and specificity respectively. The sensitivity of the intravenous glycerol test was taken in 63.0% of the Meniere's group compared to 70.3% demonstrating abnormal SP/AP. The results suggest that SP/AP ratio in transtympanic electrocochleography can be a good indicator to diagnose Meniere's disease.