Some investigators have reported higher intraocular pressure (IOP) levels in women and others in men, while some have failed to find any sex difference. It has been reported that IOP increases with age in Western populations, whereas it decreases in Japanese. Because of these contrasts, this study was planed to determine the influence of sex on IOP in various age groups in an apparently healthy population from Rawalpindi, Pakistan. Depending upon age, 5307 men and 2388 women were divided into seven groups. All subjects were examined according to standard protocols. IOP was measured by Goldmann applanation tonometer. IOP progressively increased until the age interval of 61-70 years in both sexes. The increase became statistically significant in the age interval of 51-60 years in men, while in women it was one decade earlier. The difference between the two sexes increased significantly after the age of 40 years. Ocular hypertension (IOP > 21 mmHg) was found in 5.3% and 2.1% of women and men respectively. In both sexes, distribution of IOP did not fit a normal bell-shaped curve but skewed to the right. In Pakistan, IOP increases with age in both sexes, but more markedly in women. Left eye IOP was negligibly higher in all age groups of both sexes. Ocular hypertension was found more in female than in male subjects. Menopause is associated with an increase in IOP. Menstrual cycle had no influence on IOP. Knowledge of the normal level of IOP in various age groups of both sexes may help glaucoma screeners.