Gastric carcinoma is one of the most common malignancies in Asia. Although the allelic deletion of 7q has been reportedly associated with primary gastric carcinoma tumorigenesis, no predisposing genes in this region have been identified so far. Here, we report the results of genotype and loss of heterozygosity (LOH) analysis on 7q in this tumor. A panel of nine microsatellite markers distributed over the whole chromosome 7q was used for genotyping primary gastric carcinomas. Of 72 primary tumors LOH of D7S486 occurred in 24.0% (12/50) of cases. Fine mapping with 12 additional markers flanking D7S486 resulted in LOH of 30.36% (17/56) and defined one minimal deleted region in primary gastric carcinomas, a 90-kilobase region bounded by D7S2543 and D7S486 at 7q31.2. The allelic deletion correlates statistically with clinicopathologic variables. Our data suggest a possible link between putative tumor suppressor genes and gastric carcinoma in the 7q31 region.