BACKGROUND: It is estimated that 20-30% of the annual Canadian healthcare budget may be wasted on unnecessary tests and treatments. Choosing Wisely is an initiative dedicated to addressing this problem. In Canada it has focused primarily on adult healthcare. OBJECTIVES: To describe the development, implementation and initial impact of a departmental Choosing Wisely top 5 list on paediatric care at a Canadian childrens hospital. DESIGN/METHODS: After key stakeholder input and review of current specialty society lists, an inventory of potential paediatric recommendations relevant to hospital care was generated. A survey was developed and broadly administered to rank items. Two hospitalist leaders independently scored top ranking items based on ease of implementation, measurement, alignment, and value. Five final items were chosen. Baseline measurement was achieved through various hospital databases, chart review or audit where appropriate. After appointing a physician lead and developing an implementation strategy for each recommendation, the Choosing Wisely top 5 list was launched in January 2016. Recommendations were implemented using various improvement methodologies. RESULTS: Early results nine months into the initiative show large improvements in reducing unnecessary care. For example: by not automatically giving IVIG as first-line treatment for children with typical newly diagnosed ITP, usage of IVIG has decreased from an initial baseline of 85% to 20%. In the emergency department, nasopharyngeal testing for respiratory viruses has decreased by more than 80% and routine radiography for children with low risk acute ankle injuries has decreased from 86% to 57%. CONCLUSION: Developing and implementing a Choosing Wisely top 5 list at a childrens hospital aims to promote a culture of quality, evidence-based and high-value care. We have plans for further improvements in the current project, sustaining the gains already achieved, and to expand the initiative to other areas in our institution. This model, along with lessons learned, is being shared with paediatric healthcare providers across the country through presentation at meetings and rounds, as well as publication in various media and high impact journals.