The aim: To compare efficacy of intramuscular (IM) versus intravenous (IV) ketamine for sedation in children undergoing brain MRI scanning in children. Materials and methods: Children who required elective brain MRI were selected for this study. They were randomly divided into two groups; group I received 1.5 mg/kg IV Ketamine and group II received 4 mg/kg IM ketamine. In each group supplementary 0.1 mg/kg midazolam intravenously before positioning on MRI table was given. Patients were monitored for pulse rate, SPO2, and respiratory wave. Results: Children who received IM ketamine had significantly shorter scan time and a greater success rate of sedation with first dose than the IV group. The proportions of scan interruption and scan repeat were significantly higher among the IV group than in the IM group. The scan time was longer among the IV group than in the IM group with significantly more scan interruption and repeat. Satisfaction with sedation as expressed by the technicians was significantly more in the IM group than in IV group (98.1% vs. 80.8%, P= 0.004). Conclusions: Intramuscular ketamine injection was predicted to have a better sedative success rate and takes less time to complete than intravenous admin¬istration. This makes IM ketamine more appealing in certain conditions.