A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'In patients undergoing off-pump coronary artery bypass grafting, for single or multivessel disease, does minimally invasive direct coronary artery bypass (MIDCAB) or off-pump coronary artery bypass (OPCAB) provide the superior outcome including a reduction in morbidity and mortality?'. A total of 187 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, date, journal and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. It was found that compared to OPCAB, MIDCAB surgery can offer decreased intensive care unit length of stay (4.5-57.4 h vs 5.2-52.7 h) and total hospital length of stay (4.5-8.5 days vs 5.2-12 days), with 1 paper showing a decrease in mortality at 1 year (3% vs 14%). However, there were several papers that showed significant risks with MIDCAB surgery in patients with either single or multivessel disease. These include increased risk of incomplete revascularization (29% vs 0%), significant early complications (22.5 vs 0%), urgent reintervention (16% vs 0%), repeat revascularization events (12.2% vs 3.7%), progression of native disease (4.8% vs 0.9%), rehospitalization by 3 months (20% vs 2%) and postoperative infarction (2.9% vs 1.45%). These risks did not translate to an increase in early mortality (0-1% vs 0-1.6%) or late mortality (0-3% vs 0-14%) in papers that included mid-term follow up. However, they do represent significant potential risks that cannot be overlooked when considering the use of MIDCAB. We conclude that MIDCAB is associated with greater morbidity and reintervention compared to OPCAB via sternotomy, but both techniques are equivalent in terms of operative and mid-term mortality.