Background: Robot-assisted coronary bypass (RCAB) surgery has been proposed as an alternative to conventional coronary artery bypass grafting (C-CABG) for managing coronary heart disease, but the evidence on its performance compared to other existing treatments is unclear. The aim of this study was to assess, through a systematic review of comparative studies, the safety and clinical effectiveness of RCAB compared to C-CABG and other minimally invasive approaches for the treatment of coronary heart disease. Methods: We conducted a systematic review of primary studies in the English-language literature comparing RCAB to existing treatment options (C-CABG, minimally invasive direct coronary artery bypass [MIDCAB] and port-access coronary artery bypass [PA-CAB]) following Cochrane Collaboration guidelines. Meta-analyses were performed where appropriate. Results: We reviewed 13 studies: 11 primary studies of RCAB (v. C-CABG in 7, v. MIDCAB in 3 and v. PA-CAB in 1) and 2 multicentre database studies (RCAB v. non-RCAB). The overall quality of the evidence was low. Most studies showed no significant benefit of RCAB over other treatments in a majority of outcome variables. Meta-analyses showed that RCAB had lower rates of pneumonia or wound infection than C-CABG, and shorter intensive care unit length of stay than C-CABG or MIDCAB. Individual studies showed that RCAB had some better outcomes than C-CABG (ventilation time, transfusion, postoperative pain, hospital length of stay) or MIDCAB (transfusion, postoperative pain, time to return to normal activities, physical functioning and hospital length of stay). The review of the database studies showed that RCAB was statistically superior to non-RCAB approaches in postoperative pain, renal failure, transfusion, reoperation for bleeding, stroke and hospital length of stay; however, the difference between the 2 groups in several of these outcomes was small. Conclusion: Although the findings from this review of comparative studies of RCAB appear promising and suggest that RCAB may offer some benefits to patients, in the absence of randomized controlled trials, these results should be interpreted cautiously.