The title compound, C(19)H(19)N(3)O(7)S·CH(3)OH, was synthesized from syringic acid and sulfamethoxazole. The benzene rings make a dihedral angle of 41.8 (1)° and the isoxazole ring is twisted by 74.3 (1)° from the central benzene ring. The crystal packing features O-H⋯O and O-H⋯N hydrogen bonds in which the hy-droxy groups from the main mol-ecule and methanol solvent mol-ecules serve as donor groups.