The objective of the present work was to study microbial translocation during a surgical intervention in the patients presenting with colonic neoplasms. Materials and methods. Microbial translocation was investigated during surgical interventions on 23 patients presenting with colon adenocarcinoma. The study was carried out in two steps. Stage 1 included a laparotomic incision followed by the intraoperative examination of the intra-abdominal organs. Stage II coincided with the period of maximum surgical aggression (resection of the colon). Blood samples were taken from the portal vein system and a peripheral vein. Biopsies from the colonic lymph nodes were obtained for the subsequent bacteriological study. Results. The growth of microorganisms localized in the biopsies from the colonic lymph nodes was documented in 52% of the patients, with the aerobic and anaerobic species occurring in 75% and 25% of the patients respectively. The microorganisms were identified in the blood from the portal vein in 35% of the patients (the aerobic and anaerobic species in 50% and 50% of them respectively), and in the blood from the peripheral vein in 41.7% of the patients (the aerobic and anaerobic species in 30% and 70% of them respectively). The results of the microbiological study at stage II (prior to the resection of the colon) were markedly different from those obtained during stage I. Specifically, the growth of microorganisms localized in the biopsies from the colonic lymph nodes was documented in 95.6% of the patients, with the aerobic and anaerobic species occurring in 68.2% and 27.3% of the patients respectively. The microorganisms were identified in the blood from the portal vein in 60.9% of the patients (the aerobic and anaerobic species in 7.1% and 92.9% of them respectively), and in the blood from the peripheral vein in 50.0% of the patients (the aerobic and anaerobic species in 28.6% and 71.4% of them respectively). Conclusion. The results of the present study indicate that microbial translocation constitutes one of the mechanisms underlying the development of infectious complications in the patients presenting with serious surgical pathology, such as colon adenocarcinoma, and requires prophylactic prescription of antibacterial preparations.