The purpose of this study was to estimate mean central corneal thickness (CCT) and determine whether there are any correlations between CCT, age, and sex in the adult Lithuanian population. A total of 1,650 Caucasians of Lithuanian origin (aged 18-89 years) comprising 688 (41.7%) men and 962 (58.3%) women were examined. Subjects were stratified by age into seven groups. CCT was measured using ultrasonic pachymetry. Correlations between CCT, age, and sex were sought. Mean (± standard deviation) CCT for both eyes was 544.6±30.5 μm. Mean CCT was 545.2±30.5 μm in the left eye and 544.6±30.5 μm in the right eye, and was 545.0±25.6 μm in men and 544.4±33.5 μm in women. Mean CCT was 550.8±35.7 μm in subjects aged 18-29 years, 557.5±27.6 μm in those aged 30-39 years, 551.3±31.4 μm in those aged 50-59 years, 544.0±31.4 μm in those aged 50-59 years, 544.2±31.6 μm in those aged 60-79 years, 535.1±27.8 μm in those aged 70-79 years, and 530.1±16.8 μm in those aged 80-89 years. No statistically significant difference in CCT was found between the sexes (P>0.05). However, there was a significant difference in subjects aged 18-29 years; men had higher CCT than women (P<0.05). A statistically significant negative correlation was found between CCT and age (r=-0.263, P<0.05) that was stronger in men (r=-0.406, P<0.05) than in women (r=-0.118, P<0.05). The mean CCT in adult Lithuanians was 544.6±30.5 μm, of the left eye 545.2±30.5 μm and of the right - 544.6±30.5 μm. CCT of the right eye was equal to the CCT of both eyes. Mean CCT was 545.0±25.6 μm in men and 544.4±33.5 μm in women. Young men tended to have higher CCT than women. CCT decreases over the lifetime, meaning that older people have thinner corneas. CCT's dependence on age is stronger in men.