Endothelin converting enzyme (ECE-1) is a candidate Alzheimer disease susceptibility gene. It was previously reported that western individuals homozygous for the C-338A polymorphism (AA) within the ECE1 gene promoter region are at reduced risk of developing late onset Alzheimer disease (LOAD). A further polymorphism, T-839G, is present within the ECE1 promoter region but a potential association with LOAD has not been studied. We therefore studied possible associations between these ECE1 polymorphisms and LOAD in a Chinese population. Subjects comprised 376 Chinese LOAD patients and 376 age- and sex-matched controls; all subjects were typed for the ECE1 C-338A and the T-839G polymorphisms. We report that the frequency of the 338A allele was decreased in LOAD patients compared to controls (adjusted OR =0.73; 95% CI=0.54–0.98; P=0.03). There was no significant association between T-839G genotype and LOAD, however the combined 839T/338A haplotype was significantly associated with decreased risk of LOAD (OR=0.73; 95% CI=0.57–0.93; P=0.01). This study argues that the ECE1 338A allele is protective against LOAD in a Chinese population.