Since early 2015, the media continuously confront us with images of refugee children drowning in the Mediterranean, surviving in appalling conditions in camps or walking across Europe. Within this group of fleeing children, a considerable number is travelling without parents, the unaccompanied refugee minors. While the media images testify to these flight experiences and their possible huge impact on unaccompanied minors' wellbeing, there has been no systematic research to fully capture these experiences, nor their mental health impact. In this paper, we present the first results of the ERC-Starting Grant Project 'ChildMove', whereby we followed a large group of unaccompanied refugee minors (n = 200) over the course of two years in order to document their transit experiences and the mental health impact of these experiences. Our study started in different transit countries (i.e., Greece, Italy and Belgium; an additional cross-sectional study was carried out in Libya) and from there one we followed the minors wherever they went on their migration route. During this longitudinal follow, we collected data using a mixed-methods approach (i.e., self-report questionnaires on difficult experiences and mental health symptoms and in-depth interviews) at each of the three measurement moments. The data reveal that these youngsters experience a continued series of difficult events during their trajectories, such as being detained, violence at the borders (including borders within Europe), push-backs, abuse by smugglers and other persons, appalling living conditions, racism, etc., but also after (temporary or permanent) settlement in Europe. The participants also report over the course of the follow-up high levels of mental health problems (i.e., symptoms of depression, anxiety and posttraumatic stress).