Research ethics committees (RECs) have a crucial role in protecting children in research. However, studies on REC members' perspectives on paediatric research are scarce. We conducted a qualitative study to explore Swedish scientific REC members' perspectives on ethical aspects in applications involving children with severe health conditions. The REC members considered promoting participation, protecting children and regulatory adherence to be central aspects. The results underscored the importance of not neglecting ill children's rights to adapted information and participation. REC members supported a contextual and holistic approach to vulnerability and risk, which considers the child's and parents' psychological wellbeing and the child's integrity, both short and long term. The ethical complexity of paediatric research requires continuous ethical competence development within RECs.