 The purpose of this post-approval study is to provide supplementary information relating to the use of BeneFIX in Chinese subjects with hemophilia B, especially on the safety and efficacy in different populations of Chinese hemophilia B patients, in particular in pediatric patients 6 years of age, pediatric patients 6 to 12 years of age, Previously Untreated Patients PUPs , subjects receiving prophylaxis treatment after enrollment in the study, and severe patients FIX activity 1. 