The title compound, C(8)H(10)NO(2) (+)·H(2)PO(4) (-), is a derivative of the naturally occurring compound methyl-anthranilate. The asymmetric unit comprises the 2-(methoxy-carbon-yl)anilinium cation and the dihydrogen phosphate anion. In the cation, the dihedral angle between the benzene ring plane and that through the methyl ester substituent is 22.94 (9)°. In the crystal, adjacent cations and anions form dimers through N-H⋯O and O-H⋯O hydrogen bonds, respectively. Additional N-H⋯O and C-H⋯O contacts result in a network of cation and anion dimers stacked down the b axis.