The title compound, C(10)H(13)N(3)OS, was prepared by the reaction of 4-meth-oxy-benzaldehyde and 4-methyl-thio-semicarbazide. The dihedral angle between the benzene ring and the thio-urea unit is 8.64 (7)° and an intra-molecular N-H⋯N hydrogen bond generates an S(5) ring. In the crystal, inversion dimers linked by pairs of N-H⋯S hydrogen bonds generate R(2) (2)(8) loops. The dimers are linked into (001) sheets by further N-H⋯S links.