Introduction: Pain control is one of the treatment priorities and the most important children's rights because children experience painful events since birth and during childhood due to common childhood illnesses or accidents. The aim of this study was to compare the analgesic effect of intranasal ketamine and fentanyl in children. Method: The present research is a double blind randomized clinical trial conducted on 80 children aged 3-13 years who were admitted to the Emergency Department of Sari Imam Hospital. The patients who met the inclusion criteria were randomly divided into two groups using random number generator and 40 patients were considered per group. Data were analyzed using SPSS, Mann-Whitney-U test and wilcoxon paired test. Findings: The fi ndings showed that the analgesic effect of ketamine and fentanyl are similar among the studied children and there is no signifi cant difference. In ketamine group there was signifi cant difference between the mean of pain, systolic blood pressure, diastolic blood pressure, heart rate and respiratory rate variables before and after taking ketamine, according to Willcoxon statistics and sig. smaller than 0.05. In fentanyl Group, there was signifi cant difference between the mean of pain, systolic blood pressure, heart rate and respiratory rate variables before and after taking fentanyl, according to Willcoxon statistics and sig. smaller than 0.05. There was no signifi cant difference between ketamine and fentanyl analgesic effect in terms of parental satisfaction and there was also no signifi cant difference between medical team's level of satisfaction with ketamine and fentanyl analgesic effect. Conclusion: Considering that the analgesic effect of intranasal ketamine and fentanyl on the pain control among the studied children is similar, their prescription is recommended. It is also recommended to simultaneously measure children's level of anxiety and effect of these drugs on their anxiety because children have different experiences of pain and anxiety affects measuring pain severity in future studies.