Despite the availability of the evidence to guide pain management practices, practices are often sub-optimal with children experiencing moderate to severe pain post-operatively. Limited theoretical knowledge about managing pain has been suggested as one reason for this. Several studies have identified gaps in nurses' theoretical knowledge. However, the affect of theoretical knowledge on pain management practices has not been explored. This explored whether there is a relationship between nurses' theoretical knowledge and the quality of their practices. Nurses (n=13) on one children's surgical ward were shadowed for a five-hour period during two-four shifts. Data about post-operative pain management practices were collected using a pain management checklist and field notes. Nurses (n=12) also completed the revised pain management knowledge test. Questionnaire scores were compared to the observational data. No positive relationship was found between nurses' level of theoretical knowledge and how well they actually managed pain. Nurses did not appear to routinely apply theoretical knowledge in practice. This may explain, at least in part, why pain management practices remain poor despite the evidence to guide practice being readily available. The hypothesis, put forward in other studies, that increasing nurses' theoretical knowledge about pain will improve practices may be overly simplistic.