Following a request from the European Commission (EC), the European Food Safety Authority (EFSA) assessed the scientific publication by Mesnage et al. (2016), including its relevance for the risk assessment of genetically modified (GM) maize NK603. Mesnage et al. (2016) analysed the proteomic and metabolomic profiles of maize NK603 kernels and compared those to a non-GM maize line used as a comparator. In addition, the authors quantified the levels of expression of the CP4 EPSPS protein in maize NK603. Based on this analysis, Mesnage et al. (2016) concluded that maize NK603 is compositionally non-equivalent to a non-GM maize comparator. EFSA considers that there are severe shortcomings in the experimental design, as well as uncertainties on the suitability of the test material as described by Mesnage et al. (2016). Furthermore, the interpretation of the results is incomplete, since the authors did not take into account natural variability of the endpoints analysed. Uncertainty remains with regard to potential contamination of the study materials by pathogens and the related confounding effects on the study results. The publication by Mesnage et al. (2016) does not reveal any new information that would invalidate the previous conclusions on maize NK603 made by the EFSA GMO Panel. Therefore, EFSA considers that the previous risk assessment conclusions on maize NK603 remain valid and applicable.