Pain assessment is crucial to achieving optimal pain management in children. Pain that is insufficiently controlled can have extensive short- and long-term repercussions. Many studies continue to report that children experience unnecessary post-operative pain when they are in hospital. The purpose of this literature review was to explore post-operative pain assessment practices used by children’s nurses. A literature search of databases was undertaken and inclusion criteria identified. Four themes emerged: pain assessment tools; behavioural cues; documentation; and communication between child, parent/carer and nurse. The findings showed that pain assessment tools were inadequately used, that children’s behavioural cues were misinterpreted, and that there was inconsistency in the documentation of pain scores and in communication about pain scores between children, parent/carer and nurse. Addressing the key issues identified from the articles reviewed can help improve nursing practice and care.