The incidence of somatic mutagenesis of p53 oncosuppressor protein in malignant tumors of the stomach and genetic polymorphism of p53 were studied in patients with stomach cancer on DNA samples isolated from tumor tissues obtained during surgery. The incidence of Pro/Pro genotype increased in the patients, while the percentage of Arg/Pro heterozygotes was markedly lower compared to long-living persons without cancer. The incidence of p53 somatic mutations in exons 5, 7, 8 was 70.8%; multiple mutations were detected in half of the examined patients. The relationship between the intensity of p53 mutagenesis and histological structure of the tumor was detected. The contribution of p53 genetic status to the risk of stomach cancer can be more effectively evaluated on DNA samples isolated from not only tumor cells, but also from normal tissues. The effects of epigenetic factors determining the intensity of somatic mutagenesis of p53 in tumors should be taken into account.