Background: Several negative outcomes result from poor bowel management complications, such as longer duration on mechanical ventilation (MV), a longer stay in the intensive care unit (ICU), and could increase patient morbidity rate. The Study Aim: This study was to investigate the effect of bowel regimen protocol on gastrointestinal complications among patients on mechanical ventilator a to evaluate length of ICU stay, mechanical ventilation duration and mortality rates. Research Design and Setting: A quiz experimental study was carried out between May 2021 and December 2021in three intensive care units at Assiut University Main Hospital, Egypt. Sampling: A total of 60 patients were included in the study. Study tools: The researchers utilized three tools to gather the patients' data; patient assessment tool, bowel function assessment tool and patient outcomes assessment tool. Results: The incidence of gastrointestinal complications (diarrhea and constipation) among patients in the intervention group was statistically significantly reduced to 13.3 % when compared with control group with P <0.001. There was significant improvement in general patients out comes (MV duration, length of (ICU) stay and mortality) in the intervention group in comparison with control group with (p .value < 0.05). Conclusion: Bowel regimen could significantly improve bowel function among patients in ICU, and consequently reduce constipation, diarrhea, decreases MV duration, ICU length of stay, and morality rate. Therefore, bowel regimen should be standardized as bowel routine care in ICU.