In the crystal of the title compound, C16H15N5S·C2H6OS, both the 1,2,4-triazole derivative molecules and the disordered [refined occupancy ratio = 0.604 (1):0.396 (1)] dimethyl sulfoxide solvent molecules form centrosymmetric dimers, by way of pairwise N—H...S and C—H...O hydrogen bonds, respectively. In the crystal, the two types of dimer are connected by N—H...O hydrogen bonds, forming infinite chains parallel to [101]. The packing is assisted by π–π stacking and C—H...π(ring) and N—H...π(ring) interactions.