Background/aim: Enteral feeding and immunonutrition (ImN) have been shown to be associated with a number of favorable effects in patients undergoing cancer surgery. In this prospective study, we aimed to assess the perioperative use of enteral immunonutrition in patients undergoing radical gastrointestinal surgery for malignancy. Materials and methods: Forty-one patients with malignancy were included in this study and were randomized into one of the two following nutritional strategies: enteral only (EN) or enteral with enteral immunonutrition (ENIN). These regimens were followed for 7 days perioperatively by all patients. Nutritional parameters and postoperative morbidity, mortality, and length of hospital stay (LHS) were assessed. Results: Serum prealbumin levels increased significantly in the ENIN group (P = 0.033). Moreover, patients in the ENIN group showed a more marked decrease in the rate of postoperative infections (P = 0.021) and anastomotic leakage (P = 0.018) than patients fed with EN. In the EN group, LHS was significantly longer than that in the ENIN group (18 vs. 12 days) (P = 0.032). Rates of overall morbidity and mortality were similar in the two groups (P > 0.05). Conclusion: ENIN was found to have a favorable effect on the outcome of radical gastrointestinal surgery for malignancy. Meticulous preoperative assessment of malnutrition and at least a 7-day perioperative enteral use can increase the effectiveness of immunonutrition.