In the title compound, C(4)H(6)N(2)OS(2), the dihedral angle between the five-membered heterocyclic ring and the plane of the eth-oxy group is 4.9 (2)°. The 1,3,4-thiadiazole-2-thione unit is planar, with an r.m.s. deviation of 0.011 Å from the corresponding squares plane defined by the seven constituent atoms. In the crystal, pairs of N-H⋯S hydrogen bonds link the mol-ecules into inversion dimers.