There were several reports about the correlation between pure tone threshold and speech reception threshold, but the report about the relation of pure tone threshold and maximum speech discrimination is rare. So the author studied the correlation of the pure tone threshold and the maximum discrimination of 108 bilateral sensori-neural hearing loss persons(216 ears), are also examined the correlation between pure tone threshold difference and maximum discrimination difference of both ears in same patients. The results were as follows : 1) The correlation coefficient was 0.646 between pure tone threshold and speech discrimination in 216 ears, and that was 0.746 between pure tone threshold difference and maximum discrimination difference of both ears. 2) 10 dB increase of pure tone threshold responded to 5~10% decrease of speech discrimination score. 3) So the author considered that comparison of speech discrimination score of both ears finds out whether the cause of sensori-neural hearing loss in cochlear origin and the degree of cochlear damage.