Objective: This study aimed to determine if gastric cardia adenocarcinoma (GCA) risk was associated with the lys (A or *2) allele at the rs671 (glu504lys) polymorphism within the aldehyde dehydrogenase 2 (ALDH2) gene in a Chinese Han population. We also aimed to investigateALDH2 genotypic distributions between subjects from high- and low-incidence areas for both GCA and esophageal squamous cell carcinoma (ESCC). Methods: We designed a case-control study including 2,686 patients with GCA and 3,675 control subjects from high- and low-incidence areas for both GCA and ESCC in China. TaqMan allele discrimination assay was used to genotype the rs671 polymorphism.χ2 test and binary logistic regression analysis were used to estimate the odds ratios for the development of GCA, and multivariate ordinal logistic regression was used to analyzeALDH2 genotypic distributions among different groups. Results: Compared withALDH2*1/*1 homozygotes,ALDH2*1/*2 andALDH2*2/*2 carriers did not increase the risk for GCA in the Chinese Han population (P>0.05). Interestingly, the ratio of homozygous or heterozygousALDH2 *2 carriers in high-incidence areas for both GCA and ESCC was lower than that in low-incidence areas (P<0.001). Conclusions: Genotypes of rs671 atALDH2 may not increase GCA susceptibility in Chinese Han populations. In addition, the ALDH2 genotypic distribution differs between Chinese Han populations from high- and low-incidence areas for both GCA and ESCC. Our findings may shed light on the possible genetic mechanism for the dramatic geographic differences of GCA occurrence in China.