Background: High incidence of gastric cancer (GC), its aggressive clinical course, rapid tumor dissemination, low sensitivity to chemotherapy and lack of reliable laboratory diagnostic criteria urgently require a search for the most informative markers associated with key biologic properties of the tumors. Aim: Comparative analysis of galectin-3, matrix metalloproteinase (MMP)-2, and MMP-9 levels in peripheral blood of GC patients and healthy donors, assessment of association of these markers with clinical morphological characteristics of the disease, and prognosis of overall and relapse-free survival. Materials and methods: Sixty (60) primary treatment-nave GC patients (38 men, 22 women) aged 29 to 81 years and 90 healthy donors compatible with their age and sex were included into the study. Galectin-3 was measured in EDTA plasma, MMP-2 and MMP-9 in serum with standard direct enzyme immunoassay kits "Human MMP-2 (total)", "Human MMP-9 (total)", "Human Galectin-3" (RD Systems, USA). Results: Plasma galectin-3 concentration in the GC patients was significantly higher than in the healthy controls (median 12.9 and 10.6 ng/ml, respectively; p 0.0001). No difference in serum MMP-9 levels between GC patients and control subjects were found, while MMP-2 level in the control group was significantly higher, than in the GC patients (p = 0.039). No association between galectin-3, MMP-2, and MMP-9 blood levels in the GC patients could be identified. In contrast to GC patients, there was a positive correlation of plasma galectin-3 with age in the control group (rs = 0.51, p 0.005). No associations between the biomarkers levels in blood and clinical and morphological characteristics of GC were established, except MMP-9 being higher at Т4а invasion depth as compared to the earlier Т2 level. Marked differences in the overall survival depending on plasma galectin-3 levels were found, with the cut-off level of 12.9 ng/ml: the 5-year overall survival in the patients with low galectin-3 was better, than in those with its higher level (50 and 43%, respectively; however, the difference was non-significant, р 0.1). Both overall and relapse-free survival of the GC patients was higher in those with low ( 212 ng/ml) serum MMP-2: the 5-year overall survival in this group comprised 60% versus 23% in the patients with higher MMP-2 (p = 0.018). The difference in relapse-free survival was non-significant. Serum MMP-9 levels had no significant impact on the survival of GC patients. Conclusion: The ambiguous data on the clinical role of galectin-3, MMP-2, MMP-9 in GC obtained in this study indicate the necessity of further investigation of their possible utility for the diagnostics and prognosis of treatment results.