Background Potentially inappropriate medication (PIM) and potential prescription omission (PPO) are common issues in pharmacotherapy in vulnerable populations. A first tool to assess PIM's and PPO's targeting pediatric populations: POPI <<Pediatrics Omission of Prescriptions and Inappropriate Prescriptions>> was created in 2014. Objective This study aimed to evaluate inter-rater reliability between healthcare professionals who apply POPI. Setting: Mother and child emergency ward of a university hospital. Method Twenty cases with or without PIM or PPO were identified in a previous retrospective PIM-PPO prevalence study on 15,973 patients. One doctor and one pharmacist, who participated in the creation of POPI tool, identified PIM and PPO ("gold standard response"). These cases were reviewed independently by eleven clinicians (generalists, pediatricians, pharmacists, residents), with no previous experience of this tool. Interrater agreement was calculated by using the Kappa agreement test. Main outcome measure: Inter-clinician agreement. Results A high level of agreement of PIM and PPO detection was recorded (PIM: median = 0.80; PPO: median = 0.71). Conclusion POPI demonstrated a good interrater reliability. This validation by many clinicians proves that POPI is a reliable tool. Other multicenter and prospective studies should be conducted to evaluate economical and clinical impacts of POPI.