Beta-amyloid (Abeta) peptides are derived from the endoproteolytic processing of amyloid precursor protein (APP) and play a key role in the pathogenesis of Alzheimer's disease (AD). Beta-site APP-cleaving enzyme 1 ([BACE1] also known as beta-secretase) is responsible for cleaving APP to generate neurotoxic Abeta peptides in patients with AD. The BACE1 gene is located on chromosome 11q23.3, near the recently identified region with increased lod scores for AD. The biological functional and genetic association studies indicated that the BACE1 gene might be a genetic risk factor for late-onset Alzheimer's disease (LOAD). To investigate an association between the BACE1 C786G polymorphism and sporadic LOAD in Chinese, we examined 105 LOAD patients and 130 healthy controls. Our results showed higher frequency of the 786G-allele in LOAD patients (38.6%) than that in controls (28.5%), and a statistical significance was observed for an association of the G-allele with LOAD (odds ratio [OR] = 1.58, 95% confidence interval [CI] 1.07-2.23, p = 0.02). We also found a synergetic interaction between the G-allele and apolipoprotein E allele 4 (APOE e4) status on the risk of LOAD (OR = 1.91, 95% CI 1.23-2.95, p = 0.003). These results suggest that BACE1 gene polymorphism C786G might act as an APOE epsilon4 allele-dependent risk factor for developing LOAD in Chinese.