Modified Factor IX (FIX) polypeptides and uses thereof are provided. Such modified FIX polypeptides include FIXa and other forms of FIX. Among the modified FIX polypeptides provided are those that have altered activities, typically altered procoagulant activity, including increased procoagulant activities. Hence, such modified polypeptides are therapeutics.本發明提供經修飾之第九因子(FIX)多胜肽及其用途。此等經修飾之FIX多胜肽包括FIXa及其他形式之FIX。在所提供之經修飾之FIX多胜肽中有活性已改變,典型地為促凝血活性已改變,包括促凝血活性增加之經修飾之FIX多胜肽。因此,此等經修飾之多胜肽為治療劑。