Background <p>Laparoscopic total mesorectal excision (TME) has become the standard surgical treatment for rectal cancers, despite being a technically challenging procedure due to the straight and rigid nature of the laparoscopic instrument within a narrow bony pelvis. A robotic system with multi-joint instruments, three-dimensional vision, and improved ergonomics was introduced, however it is not yet cost-effective. Recently, several articulating laparoscopic instruments have been developed and introduced as substitutes for multi-joint robotic system instruments. The prospective study aims to demonstrate that the positive rate of circumferential resection margin following laparoscopic surgery with articulated laparoscopic instruments is non-inferior to that of robotic surgery in the treatment of rectal cancer.</p> Methods/design <p>Patients with primary rectal cancer who are treated with low anterior resection using articulated laparoscopic instruments will be included in the study. Participating colorectal surgeons must use articulated laparoscopic instruments at least during TME. We hypothesize that the positive rate of circumferential resection margin after robotic surgery will be 6%, 3 based on the previous studies. A trial with 157 patients contributing to the primary outcome analysis would have 80% power to declare non-inferiority with a 5.2% non-inferiority margin, assuming a 10% dropout rate. To compare laparoscopic TME group and robotic TME group, we adjust for variables such as gender, T stage, N stage, sphincter saving status, and preoperative chemoradiation using propensity score matching. The primary end-point of this study is cicumferential resection margin after surgery.</p> Discussion <p>Based on this study, we hope to demonstrate the efficacy and viability of articulated laparoscopic instruments in the treatment of rectal cancer at a lower cost than robotic surgery.</p> Trial registration <p>Clinical Research Information Service KCT0008896. Registered on 15 August 2023.</p>