Hypoxia-inducible factor-asparagine dioxygenase (, HIF hydroxylase) is an enzyme with systematic name hypoxia-inducible factor-L-asparagine, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating). This enzyme catalyses the following chemical reaction:
<blockquote> hypoxia-inducible factor-L-asparagine + 2-oxoglutarate + O<sub>2</sub> hypoxia-inducible factor-(3S)-3-hydroxy-L-asparagine + succinate + CO<sub>2</sub> </blockquote>
Hypoxia-inducible factor-asparagine dioxygenase contains iron, and requires ascorbate.