To systematically review the literature evaluating efficacy and adverse events of propranolol treatment for infantile hemangiomas, we searched the MEDLINE and Cochrane databases for all studies examining the response of infantile hemangiomas (IHs) to propranolol published between June 12, 2008, and June 15, 2012. Forty-one studies with 1,264 patients were included; 74% of patients were female and approximately 30% had received other treatments before propranolol. Propranolol was initiated at a mean age of 6.6 months at a mean dose of 2.1 mg/kg/day and for a mean treatment duration of 6.4 months. The response rate for patients with IHs treated with propranolol was 98% (range 82%–100%), with response rate defined as any improvement with propranolol. Treatment response rates were comparable for studies evaluating IHs at specific sites, such as periorbital IHs. Studies that followed patients after treatment completion reported IH rebound growth in 17% of patients. There were 371 adverse events reported in 1,189 patients. The most common adverse events were changes in sleep (n = 136) and acrocyanosis (n = 61). Serious adverse events were rare, with reports of symptomatic hypotension in five patients, hypoglycemia in four, and symptomatic bradycardia in one. This systematic review of 1,264 patients treated with propranolol for IHs showed a high rate of efficacy and a low rate of serious adverse events.