We explored the collateral harm in Dutch children and adolescents during the COVID-19 pandemic from experience of paediatricians via an open question distributed via the website of the Dutch Paediatric Society. From the end of March till the first week of July, we received 51 reports of collateral harm involving mostly very young children with mainly acute physical problems but also social problems. In older children, several cases of diabetic ketoacidosis were reported. Our results show that delaying care can lead to seriously ill children, life-threatening situations and that in some cases it can even lead to death. If we want to avoid such a delay at a possible second peak of Corona, general care providers and paediatricians have to join forces and find new ways of working. Systematic data collection of collateral harm in children is needed to be able to intervene adequately.