<h4>Background</h4>This study aims to elucidate the effects of renin-angiotensin system inhibitors (RASIs) on renal function throughout the stoma period in patients undergoing ileostomy formation and subsequent stoma closure following rectal cancer surgery.<h4>Methods</h4>In this single-center retrospective study, patients who underwent rectal resection with temporary ileostomy between January 2010 and December 2020 were divided into two groups based on RASI use. This evidence concerns the gene REN and rectal cancer.