2-(4-Acetamido-benzene-sulfonamido)-3-methyl-butanoic acid.

In the title compound, C(13)H(18)N(2)O(5)S, the benzene ring and the acetamide group are almost coplanar [dihedral angle = 5.6 (3)°], and the amine group projects almost vertically from this plane [C-C-S-N = -84.5 (7)°]. A short intra-molecular C-H⋯O contact occurs. In the crystal, O-H⋯O, N-H⋯O and N-H⋯(O,O) hydrogen bonds lead to a three-dimensional network. One of the methyl groups of the isopropyl residue is disordered over two orientations in a 0.747 (16):0.253 (16) ratio.