As a preliminary experiment on the measurement of translucent properties of natural and artificial teeth, the individual discrimination threshold for luminous transmittance difference was checked according to the principle of haze comparison by the paired difference test. A total of 20 males and females who were 18-30 years old participated in this study as experimental subjects and the following results were obtained : (1) the average for the actual least perceptible haze difference was 0.76%, (2) the larger haze differences were more easily distinguished, but it was not always the case.