The intraocular pressures of 9,461 persons are given by age-sex groups. Constants which describe the frequency distribution of intraocular pressure have been calculated by total number of eyes examined as well as by the higher pressure value of each patient. Intraocular pressures as measured by the Schiøtz tonometer do not have a normal (gaussian) distribution. The shape of the frequency-distribution curve of intraocular pressure also changes slightly as the population ages. These changes are discussed in relation to glaucoma screening with the Schiøtz tonometer. Precise screening levels for diagnostic referral are difficult to achieve with the present design of the Schiøtz tonometer.