The EOG was determined in 130 normal subjects. The mean value was 2.42, the interindividual standard deviation 0.42. The difference between the right eye and the left eye was not significant, neither was the difference between a group of youngsters (20-30 years) and an older age group (50-55 years). In another group of 48 normal subjects, 10 or more EOGs were determined per individual. The intraindividual standard deviation was not a fixed number, but appeared to be dependent on the height of the EOG, being approximately 10% of the EOG value. This is a confirmation of one of our previous observations.