In 1983 the board of the Japan Society for Equilibrium Research presented a standard of stabilometry including both routine and precision tests. The precision test consists of measurments and analyses conducted automatically with the use of a computer. However, the items of the precision test are not specified. The purpose of this study is to describe the items of the precision test and to determine the normal range of each item in healthy adults.The subject was requested to stand on a stabilometer with the feet close together. The sway of the body center of gravity was recorded for 60 seconds with an X-Y recorder and stored in a microcomputer with a sampling rate at 20 Hz. Each examination was performed with eyes open and eyes closed. From the stored data, unit locus length, forward-backward and right-left diameters, area, standard deviation, skewness and kurtosis of amplitude probability density distribution, velocity, center of the sway and power spectrum were calculated with a program designed for this experiment.Ninety one healthy subjects aged 15 to 82 years were examined.1 . Unit locus length, F-B and R-L diameters and sway-area were required for evaluation of the size of the sway.2. Skewness, kurtosis, and the ratio of F-B to R-L diameter were indispensable to determine the pattern of the sway.3. The center of the sway was useful for evaluation of the shift of the body center of gravity in the upright standing posture.4. Vector analysis of velocity was necessary as a parameter of the characteristics of the sway and to determine the direction of the sway.5. Power "spectrum was essential to observe the amplitude in connection with the frequency of the sway.6. In subjects over 50-years of age, the values of each item increased with age. Therefore, the values obtained in subjects aged 20 to 49 are presented as a standard for stabilometry in healthy adults.