In enzymology, an aspartate-semialdehyde dehydrogenase (EC 1.2.1.11) is an enzyme that is very important in the biosynthesis of amino acids in prokaryotes, fungi, and some higher plants.

This pathway also produces diaminopimelate which plays an essential role in bacterial cell wall formation.

There is particular interest in ASADH as disabling this enzyme proves fatal to the organism giving rise to the possibility of a new class of antibiotics, fungicides, and herbicides aimed at inhibiting it.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of a donor with NAD+ or NADP+ as acceptor.

It also contains the yeast and fungal Arg5,6 protein, which is cleaved into the enzymes N-acetyl-gamma-glutamyl-phosphate reductase and acetylglutamate kinase.