The title mol-ecule, C(11)H(13)NO(3), has its propanoic acid group in an extended conformation, such that the mol-ecule is nearly planar, with a mean deviation of 0.036 Å [the maxima being 0.106 (1) and 0.110 (1) Å for the two methyl-ene C atoms]. The NH group forms an intra-molecular hydrogen bond with the acetyl group; in the crystal COOH group forms a centrosymmetric hydrogen-bonded dimer.