(E)-4-(2,3-Dihydro-1,3-benzothia-zol-2-yl-idene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one.

In the title compound, C(17)H(13)N(3)OS, the dihedral angle between the ring systems is 2.22 (5)°. The N-H grouping participates in both intra- and intermolecular N-H⋯O hydrogen bonds, the latter leading to dimers related by a twofold rotation axis.