An increasing number of studies suggest that cholesterol plays an important role in regulating beta-amyloid (Aβ) metabolism in Alzheimer’s disease (AD). One of the most important mechanisms for the elimination of excess brain cholesterol is its conversion into the 24S-hydroxycholesterol catalyzed by cholesterol 24S-hydroxylase (CYP46). Preliminary evidence indicates that an intron 2 CYP46 T/C gene polymorphism<i></i>is associated with increased brain Aβ load and higher risk of AD. A case-control study utilizing a clinically well-defined group of 321 sporadic AD patients and 315 control subjects was performed to test this association. Our results indicate that the intron 2 CYP46 C/C genotype may predispose to AD, and this association is independent of the apolipoprotein E genotype.