The risk assessment of GM stacked events, which are considered as a new GMO in the EU, could be less extensive than the assessment of the parental GM events. This will be the case when the latter have been proven to be safe for the human health and the environment for the same uses as the GM stacked event. Criteria for the risk assessment of GM stacked events combining positively assessed GM parental lines are proposed. Molecular and comparative analysis data are put forward as minimum requirements. Additional food/feed safety testing and environmental studies are considered relevant on a case-by-case basis.