To evaluate the prognostic value of ultrasound and MRI findings in patients with infantile hemangioma undergoing propranolol therapy. This study was based on retrospective interpretation of prospectively acquired data. Thirty-eight consecutive patients (28 females and 10 males; mean age ± standard deviation, 3.2 ± 2.2 months) who underwent propranolol treatment for infantile hemangioma were included. Pre-treatment ultrasound images were assessed in terms of echogenicity, lesion height and vascularity. Presence of prominent intratumoral fat, non-fat septa, and enhancement pattern on MRI were retrospectively evaluated. Mann-Whitney test, chi-square, and Fisher's exact tests were used to compare imaging parameters between patients with treatment success and failure. All patients underwent ultrasound and 15 patients underwent MRI. A total of 24 patients showed successful treatment. Between patients with treatment success and failure, there were significant differences in increased vascularity on pre-treatment ultrasound (19/24 vs. 6/14, p = 0.025), decreased vascularity on post-treatment ultrasound (21/24 vs. 5/14, p = 0.001), and prominent intratumoral fat on MRI (1/8 vs. 5/7 p = 0.033). There were no significant differences in echogenicity, lesion height on ultrasound, non-fat septa and MR enhancement pattern. Increased vascularity on pre-treatment ultrasound was significantly associated with successful treatment for propranolol therapy in patients with infantile hemangioma, whereas prominent fat component on MRI was significantly associated with treatment failure.