Background: Recently, propranolol has been found to be an effective treatment agent for infantile hemangiomas. Several studies have documented the effectiveness of propranolol in involution of infantile hemangiomas. The known side effects of propranolol include bronchospasm, hypoglycemia, bradycardia, hypotension, hyperkalemia, cool extremities,sleep disturbance, etc. However, the exact prevalence of adverse effects of this drug in Korean infants is unclear. Objective: The purpose of this study was to evaluate the efficacy and side effects of propranolol treatment in Korean patients with infantile hemangiomas. Methods: A total of 29 patients diagnosed with infantile hemangioma were treated with propranolol ranging from 1.5 to 2.5 mg/kg/day given either 2 or 3 times per day. Echocardiography and vital signs, blood glucose levels, and serum electrolytes were checked before and after each additional increased dose thereafter, and also during or at the end of the treatment period. All patients with IH took photographs and their parents were asked questions regarding their side effects at intervals of two months. Results: The mean age at treatment initiation was 3.9 months, and the average duration of treatment was 10.4months. Most of the patients (82.98%) showed good response with a clearance of 75% or more. Three (10.34%)patients had sleep disturbance and one (3.45%) had hyperkalemia. No patient was reported to have severe side effects such as symptomatic hypoglycemia, bradycardia, and hypotension. Conclusion: Based on these results, propranolol therapy is a very safe and highly effective modality for the treatment of Korean infants with infantile hemangiomas.