α-Aminobutyric acid (AABA) is an isomer of the amino acid aminobutyric acid with chemical formula C4H9NO2. It has two other isomers, gamma-aminobutyric acid (GABA) and beta-aminobutyric acid.
It is a key intermediate in the biosynthesis of ophthalmic acid or ophthalmate, which was first isolated from calf lens.