The title compound, C(13)H(14)N(2)O(2), an isoxazol-5-one derivative, was synthesized by a one-pot, three-component condensation reaction of methyl acetoacetate, hydroxy-lamine hydro-chloride and 4-(dimethyl-amino)benzaldehyde. All the non-H atoms are co-planar [r.m.s deviation = 0.0039 Å], with a Z configuration about the C=C bond. The dihedral angle between the phenyl ring and the isoxazole ring is 2.58 (19)°.