Coronary endarterectomy (CE) may provide a useful adjunct to coronary artery bypass grafting (CABG) in patients with extensive, diffuse coronary atheroma. However, concerns regarding its morbidity and mortality have created uncertainty as to the role of CE in the current era. The aim of this study was therefore to quantitatively summarize the short- and long-term outcomes of CE. Twenty observational studies were identified by systematic literature search, incorporating 54 440 patients (7366 CABG + CE; 47 074 CABG only), which were analysed using random-effects modelling. Heterogeneity, subgroup analysis, quality scoring and risk of bias were assessed. Primary end-points were 30-day mortality and perioperative and postoperative myocardial infarction (MI). Secondary end-points were postoperative morbidity, intensive care unit (ITU) stay, hospital stay and long-term graft patency. Adjunctive CE significantly increased 30-day mortality [odds ratios (OR) = 1.69, 95% confidence interval (CI) [1.49-1.92], P <0.00001], perioperative (OR = 2.10, 95% CI [1.82-2.43], P <0.00001) and postoperative MI (OR = 3.34, 95% CI [1.74-6.41], P = 0.0003) when compared with CABG alone. Furthermore, postoperative ventricular arrhythmias, pulmonary complications, renal failure and inotrope use were significantly greater in patients undergoing adjunct CE. CE also increased ITU and hospital stay and reduced angiographic patency at the last follow-up (OR = 0.57, 95% CI [0.36-0.88]). Increased 30-day morbidity and mortality continues to raise concerns over the safety of adjunct CE. Furthermore, the procedure can be associated with worse long-term graft patency. To better determine whether CE should remain a viable adjunct to CABG, novel studies must focus on collecting prospective data with homogeneous inclusion criteria for CE as well as isolating outcomes for different coronary vessels and standardizing postoperative anticoagulation.