Alzheimer’s disease (AD) is neurodegenerative disease, characterized by β-amyloid deposition, hyperphosphorylation of tau protein and formation of fibrillary tangles. Angiotensin-converting enzyme (ACE) has been investigated as a candidate gene that might be associated with Alzheimer’s disease. ACE gene has an insertion deletion polymorphism (I/D) of a 287 bp Alu repetitive sequence in intron 16. In our study, we investigated this ACE I/D polymorphism and AD association in Lebanese patients by performing ACE genotyping of 45 AD patients and 48 age-matched controls from Dar Al-Ajaza Al-Islamia Hospital in Beirut. There was a significant difference in ACE genotypes between AD patients and controls. Our study suggest that ACE polymorphism is associated with Alzheimer’s disease having I/I genotype as a risk factor.