Hearing acuity was measured in 164 normal children aged from 4 to 6 years by means of play-audiometry, and, at the same time, the mental capacity of these children was examined using Tanaka mental test for young children. Contrary to the author's presumption, no correlation was found between the hear- ing acuity and the mental capacity in these children examined.From this fact the conclusion was drawn that the improvement of average normal acuity of hearing in young children in response to the getting older was probably due to other factors than the development of their mental capacity.