Study objective: To determine the cost-effectiveness of 3 clinical decision rules in comparison to Australian and New Zealand usual care: the Children's Head Injury Algorithm for the Prediction of Important Clinical Events (CHALICE), the Pediatric Emergency Care Applied Research Network (PECARN), and the Canadian Assessment of Tomography for Childhood Head Injury (CATCH). Methods: A decision analytic model was constructed from the Australian health care system perspective to compare costs and outcomes of the 3 clinical decision rules compared with Australian and New Zealand usual care. The study involved multicenter recruitment from 10 Australian and New Zealand hospitals; recruitment was based on the Australian Pediatric Head Injury Rules Study involving 18,913 children younger than 18 years and with a head injury, and with Glasgow Coma Scale score 13 to 15 on presentation to emergency departments (EDs). We determined the cost-effectiveness of the 3 clinical decision rules compared with usual care. Results: Usual care, CHALICE, PECARN, and CATCH strategies cost on average AUD $6,390, $6,423, $6,433, and $6,457 per patient, respectively. Usual care was more effective and less costly than all other strategies and is therefore the dominant strategy. Probabilistic sensitivity analyses showed that when simulated 1,000 times, usual care dominated all clinical decision rules in 61%, 62%, and 60% of simulations (CHALICE, PECARN, and CATCH, respectively). The difference in cost between all rules was less than $36 (95% confidence interval –$7 to $77) and the difference in quality-adjusted life-years was less than 0.00097 (95% confidence interval 0.0015 to 0.00044). Results remained robust under sensitivity analyses. Conclusion: This evaluation demonstrated that the 3 published international pediatric head injury clinical decision rules were not more cost-effective than usual care in Australian and New Zealand tertiary EDs. Understanding the usual care context and the likely cost-effectiveness is useful before investing in implementation of clinical decision rules or incorporation into a guideline.