The threshold gap between test and retest is considered to the one of malingering, pathologic process, or being within physiological range. So, the authors performed the test-retest with puretone audiometry for the purpose of evaluation of physiological threshold variation. The subjects were 121 ears of normal hearing group, 61 ears of OMPC group and 57 ears of sensorineural deafness group, and the conclusions were summarized as follows : 1) The average test-retest threshold gap was about 1.2-1.9 dB in each frequency of normal group. And the speech range had narrower gap, but the higher or lower range, the wider gap was. 2) The average threshold gap was about 0.1-1.2 dB in OMPC group. And there was no rule depending on each frequency range but much more variation was found in each individuals than normal group. 3) The average threshold gap was about 1.0-2.5 dB in sensorineural deafness group. There was wider gap in higher or lower frequency range than in speech range, and much more variation in each individuals than normal group. 4) Except lower tone and part of higher tone of OMPC group, there was higher value in first measurement of hearing threshold than the second. 5) The widest threshold gap was 30 dB in each group ; in 95% reliablity, the physiological threshold variation was within 10.8-15.0 dB of normal group, 18.0-21.0 dB of OMPC group and 13.2-23.0 dB of sensorineural deafness group. 6) Comparing with groups, there were more variation of threshold in OMPC, sensorineural, normal group in that order.