Purpose: To investigate the frequency of Alzheimer-related dementia in patients with pseudoexfoliation syndrome (PEX). Methods: Sixty-seven patients with PEX and 67 age-, gender-, and educational-background-matched control subjects were compared for the presence of Alzheimer-related dementia according to DSM-IV-TR. The effects of cataract, glaucoma, additional ocular and systemic disease on the dementia incidence were also evaluated in patients with PEX and the control group. Results: The frequency of Alzheimer-related dementia was higher in patients with PEX (p = 0.0001). The frequency of dementia in patients who had cataract was higher than in patients without cataract (p = 0.003). There was also an association between additional ocular disease and dementia (p < 0.05). However, there was no association between systemic disease and dementia (p > 0.05). Furthermore, there was no difference for the frequency of dementia between patients who had glaucoma or not among patients with PEX (p = 0.953). Conclusion: The increased frequency of Alzheimer-related dementia in patients with PEX is important and a possible association between PEX and Alzheimer's disease could be present.