Background. Recommendations for the treatment of locally advanced gastric cancer are based on the clinical stage of the patient’s disease, and the prognosis of the course of the disease (especially for locally advanced processes) directly depends on the ability of the tumor to peritoneal spread. Objective. Assessment of the effect of clinical and morphological markers (tumor localization, stage of the disease according to T, N criteria, lesion of the greater/lesser omentum, morphological type of tumor) on the survival rate of patients diagnosed with locally advanced gastric cancer after radical surgical treatment. Methods. For a retrospective analysis, 124 patients aged 29 to 86 years (mean age 65.69±10.09 years; 95% CI: 63.90-67.49) diagnosed with gastric cancer stages I-III who received only surgical treatment from 2015 to 2018 in the St. Petersburg City Clinical Oncological Dispensary were selected. All patients underwent radical surgical treatment (resection/gastrectomy) followed by staging of the disease according to the TNM system (7th edition) with additional assessment of the lesion of the greater/lesser omentum. Results. The prognostic value of the degree of metastatic lesion of the lesser and greater omentum was determined. The median overall survival (OS) of patients without omentum lesions was not reached at the time of assessment (follow-up period, 42-54 months). The median OS in patients with the lesser omentum lesion was 57 months (95% CI: 19.0-57.0), which was 28 months higher than the median OS in patients with isolated lesions of the greater omentum (29 months, 95% CI: 29.0-29.0) and exceeded the median OS by 38 months in patients with combined lesions of the lesser and greater omentum (19 months, 95% CI: 11.0-36.5). According to the results of the multivariate analysis (model significance; p<0.0001), the criteria T(p= 0.0090) and N (p=0.0016) had a significant effect on the OS index; a more favorable effect on the OS index was exerted by the lesion of the lesser, rather than the greater omentum, which allows an increase in OS by 12-60% (p=0.4046). Conclusion. Our study showed that the lesion of the greater omentum in gastric adenocarcinomas should be considered as a factor of poor prognosis, and total omentectomy during radical gastrectomy does not prevent the development of relapse and death from disease progression.