© TÜBİTAK.Background/aim: Critically ill patients are at risk of developing gastrointestinal (GI) bleeding due to stress causing mucosal damage. Aim of the study was to determine the effect of oral/enteral nutrition with or without concomitant pantoprazole on upper GI bleeding in low risk critically ill patients. Materials and methods: This was a prospective, randomized, open-label, multicenter study conducted with intensive care unit (ICU) patients receiving oral/enteral nutritional support. Patients were randomly assigned into two groups including intervention group (received oral/EN plus pantoprazole) and control group (received only oral/EN). Results: A total of 300 patients (intervention group: 152, control group: 148) participated in the study. Overall, 226 (75%) patients were fed by orally and 74 (25%) patients fed by enteral tube feeding. Median duration of nutritional support 4 (range: 2–33) days. Overt upper GI bleeding was noted only in one patient (0.65%) who was in the intervention group. The overall length of ICU stay of 4 (2–105) days, while ICU stay was significantly longer in the intervention group than in the control group (P = 0.006). Conclusions: Our findings seems to indicate that in patients who are at low risk for GI bleeding and under oral/enteral nutritional support, the use of PPIs may not reduce the risk of bleeding, however these results are imprecise because of low event (GI bleeding) rate and limited power.