Intraocular pressure (IOP) was measured in a mixed population of 12,803 apparently healthy employed people. Mean IOP was 13.5 +/- 3.3 mmHg, without sex difference. Frequency distribution demonstrated skewness towards high values. IOP weakly correlated with age (R = 0.06), and older subgroups showed more marked skewness, but further analysis showed this effect to be spurious. The correlations of IOP with heart rate and with systolic blood pressure were small, but stronger than with age (R = .16 and .15, respectively). Moreover, when corrected for heart rate, the effect of age was nullified. Other factors found to be correlated with IOP included blood glucose and hemoglobin concentration, smoking, and height. None of these factors significantly increased the correlation between IOP and heart rate or blood pressure, and the skewness was not fully explained by any of these factors or their combinations. The value of the epidemiologic approach to detection of factors responsible for ocular hypertension is stressed.