BACKGROUND: Despite advancements in pain management, children have remained undertreated for postoperative pain. Data regarding the practice of post-operative pain management in paediatric patients remains less available in the developing world. This study was aimed at evaluating practice of postoperative pain management in under five children. METHODS: A prospective cross sectional one-year study was conducted on all paediatric patients who underwent major paediatric surgical procedures from February 1, 2020 to January31, 2021, at a tertiary hospital in Addis Ababa, Ethiopia. RESULT: A single type of analgesic medication was used in 67.1% patients. Analgesic medications were administered on standing base only in 64.4% of patients. Patients’ charts had no documentation of pain assessment both in the neonatal intensive care units and wards.32.89 % of assessed patients had moderate to severe pain record. CONCLUSION: Significant number of patients suffer from post-operative pain because of absence of proper pain assessment and inadequate administration of analgesic medication.