Pain assessment in children can be extremely challenging. Most professional bodies recommend that parents or carers should be involved with their child's pain assessment; but the evidence that parents can accurately report pain on behalf of their children is mixed. Our objective was to examine whether there were differences in post-operative pain score ratings between the child, nurse and parent or carer after surgery. Cognitively intact children aged four upwards, undergoing all surgical procedures, whose parents were present in the post-anaesthetic recovery unit (PACU), were studied. Thirty-three children were included in the study. The numerical rating scale was used to rate the child's pain by the child, nurse and parent on arrival to the PACU and prior to discharge. We found strong correlations between children's, nurses' and parent's pain scores on admission and discharge from PACU. The intraclass correlation coefficient of pain scores reported by children, nurses and parents was 0.94 (95% confidence intervals 0.91-0.96, P<0.0001). In cognitively intact children, it is adequate to manage pain based upon the assessment of children's and nurses' pain scores alone. The numerical rating scale appeared to be suitable for younger children. Whilst there are benefits of parents being present in recovery, it is not essential for optimizing the assessment of pain.