This report summarizes the contents and outcomes of the Scientific Stakeholder Meeting on Nanomaterials in the Environment which took place on the 10th and 11th October 2017 at the headquarters of the German Environment Agency (UBA) in Dessau-Rosslau, Germany. The meeting focused on regulatory relevant results of German and European research projects on nanomaterials in the environment which are carried out or finalised in the current years. By this, it gave a forum to present the state of the knowledge on environmental nanosafety in a regulatory context as well as to discuss the scientific results and their regulatory relevance between affected stakeholders. It included key note talks, invited platform presentations as well as poster presentations. A Knowledge Café provided the opportunity to discuss selected topics with regard to environmental safety of nanomaterials in smaller groups. The meeting was closed with a discussion on the lessons learned highlighting the outcomes of the meeting by the views of different stakeholders.”