Background <p>Inadequate bowel perfusion is among risk factors for colorectal anastomotic leaks. Perfusion can be assessed with indocyanine green fluorescence angiography (ICG) during colon resections. Possible benefits from its systematic use in high-risk patients with rectal cancer remain inconsistent. This study aimed to evaluate the surgical modifications induced by ICG assessment during rectal cancer surgery and associated anastomotic leaks.</p> Methods <p>This prospective before and after cohort study was conducted in a single Canadian high-volume colorectal surgery center. Eligible patients were undergoing a&#xa0;low anterior resection for rectal cancer below 15&#xa0;cm from the anal margin. Stapled and handsewn coloanal anastomoses were included. The experimental group was recruited prospectively, undergoing surgery using fluorescence angiography with ICG. The control group was built retrospectively from consecutive patients who had been operated on without ICG, prior to its implementation.</p> Results <p>Each cohort included 113 patients. The use of ICG led to modifications from initial surgical plan in 10.6% of patients, with no occurrence of anastomotic leaks in this specific group. When comparing leak rates, using ICG seemed to be protective, but this could not be statistically proven, overall (13.3% vs. 6.2%, <i>p</i> = 0.07), nor for handsewn coloanal anastomoses (11.8% vs. 5.9%, <i>p</i> = 0.67). A lack of power could explain such non-significant results, especially with low overall anastomotic leak rates recorded.</p> Conclusion <p>ICG influenced ultimate proximal resection margin in a clinically relevant proportion of cases. It might be associated with reduced leak rates although not formally proven with this data. This technology is safe and easy to apply in high-volume colorectal centers.</p>