The prevalence rate of pseudoexfoliation among persons in the Framingham Eye Study, a population-based survey, increased from 0.6% for ages 52 to 64 years to 2.6% for ages 65 to 74 years to 5.0% for ages 75 to 85 years. Age-adjusted rates showed a statistically significant 2.3 to 1.0 female to male ratio. Pseudoexfoliation was associated with higher intraocular pressure levels and more frequent senile lens changes, but the latter relationship was not statistically significant. The age-specific prevalence rates for the Framingham population are similar to those reported from a mass screening of subjects in Norway, where the condition is thought to be especially common. Some of the previously reported geographic variations in prevalence rates may be due to differences in disease definitions, subject selection, and examination conditions.