The European Food Safety Authority (EFSA) Panel on Genetically Modified Organisms (GMO Panel) has published its assessment on the safety of the six-event stack genetically modified (GM) herbicide-tolerant and insect-resistant maize Bt11 × MIR162 × MIR604 × MON 89034 × 5307 × GA21. The Scientific Opinion is published based on the application EFSA-GMO-DE-2018-149 under Regulation (EC) No. 1829/2003 received from Syngenta Crop Protection NV/SA.