The objectives of this study were to evaluate: (1) the dose response and (2) the pharmacokinetics (PK) and pharmacodynamics (PD) of intravenous (IV) administration of CINRYZE for the treatment of acute angioedema attacks in children above and below 25 kg and less than 12 years of age with hereditary angioedema (HAE); and (3) to determine the safety and tolerability following IV administration of CINRYZE in this study population.