We report two cases of inflammatory myofibroblastic tumor (IMT) of the lung in a 4-year-old boy and a 7-year-old girl. We performed dynamic contrastenhancement computed tomography in both of our cases and dynamic contrast enhancement magnetic resonance imaging (MRI) in one case. These dynamic studies showed a demarcated mass with delayed enhancement in both cases. A T1-weighted MR image shows a mass with homogeneous low signal intensity, and a T2- weighted image shows a mass with slightly high signal intensity. A post-contrast-enhanced T1-weighted image demonstrates homogeneous enhancement. We speculate that the delayed enhancement could be attributed to the abundant fibrous tissue, which was the main structural material of the tumor. This same finding has been described in previous reports of IMT in other organs.