Pain assessment is a difficult task for parents at home following children's surgery. The purpose of the present study was to confirm the psychometric properties of a behavioural measure of postoperative pain developed to assist parents with pain assessment in children aged 7-12 years following day surgery. The study also examined the reliability and validity of the measure with children aged 2-6 years. Participants were 51 parents of children aged 7-12 years and 107 parents of children aged 2-6 years. For the 2 days following surgery, parents completed a pain diary that included global ratings of their children's pain and the 15-item Parents' Postoperative Pain Measure (PPPM). The older children provided self-reports of their pain intensity. The PPPM items showed good internal consistency on the two postoperative days for both samples (alpha's=0.81-0.88) and scores on the PPPM were highly correlated with children's (for the older children) and parents' (for the young children) global ratings of pain (r's=0.53-0.72). As global pain ratings decreased from Days 1 to 2, so did scores on the PPPM. Scores on the PPPM were successful in discriminating between children who had undergone low/moderate and high pain surgeries. The results of this study provide evidence of the reliability and validity of the PPPM as a measure of postoperative pain among children aged 2 through to 12 years.