AIM: To analyze the prevalence of the two commonest thrombophilic mutations, factor Ⅴ Leiden and prothrombin G20210A, in patients with gastric cancer.METHODS: One hundred and twenty-one patients with primary gastric carcinoma and 130 healthy subjects,comparable for age and sex, were investigated. Factor Ⅴ Leiden was detected by using polymerase chain reaction and restriction enzyme digestion, and prothrombin G20210A gene mutation by allele-specific PCR.RESULTS: Among the 121 cancer patients, factor Ⅴ Leiden was found in 4 cases (GA genotype: 3.3%) and prothrombin G20210A in 10 cases (GA genotype: 8.3%).Of the 130 control subjects, factor Ⅴ Leiden was detected in 6 cases (GA genotype: 4.6%) and prothrombin G20210A in 8 cases (GA genotype: 6.1%). No double heterozygous carriers of both mutations were found in either group. The prevalence of both factor Ⅴ Leiden and prothrombin G20210A variant was not statistically different between the cancer patients and the healthy subjects.CONCLUSION: Our study suggests that, in gastric cancer, the risk factors of thrombophilic cancer state are on acquired rather than on a genetic basis and that prothrombin G20210A does not seem to be a cofactor in gastric cancer pathogenesis.