The purpose of this study was to identify factors of importance for children's participation in medical and nursing care. A method close to the critical incident technique was used. A total of 92 stories told by staff and containing different levels of children's participation in decision making were analysed. The factors affecting children's participation in decision making were grouped into six categories: the child's protest, the child's age and maturity, the role of parents, attitudes of staff, the time factor and alternative solutions to the problem. This study shows that in certain cases children can affect their situation, bus also that violating actions are performed on children.