In the title compound, C(12)H(17)NO(5)S, the orientations of the 2-ethyl-2-amino-3-hy-droxy-propano-ate group and the 4-methyl-sulfonyl moiety towards the aromatic ring are periplanar and (-)-anti-clinal, respectively. In the crystal packing, the dominant inter-action is O-H⋯N hydrogen bonding, which generates a chain running along [100]. N-H⋯O and C-H⋯O interactions are also observed.