To identify factors that influence nurses' pain management in children. A qualitative design was used. Twenty-one nurses working in one paediatric department were interviewed using semi-structured interviews. Data were analysed by means of content analysis. The way nurses manage pain in children is affected by factors such as co-operation between nurses and physicians and between nurses and patients, children's behaviour, routines in the organisation, and the experience and knowledge of nurses. Pain management in children could be improved through increased co-operation between nurses, physicians and parents. Planning time and good routines could facilitate pain management. Education about pain management and children's pain behaviour might also improve nurses' ability to manage pain in children.