Ethyl 5-{[(E)-2-(isonicotinoyl)hydrazinyl-idene]methyl}-3,4-dimethyl-1H-pyrrole-2-carboxyl-ate dihydrate.

In the title compound, C(16)H(18)N(4)O(3)·2H(2)O, the dihedral angle between the pyrrole and pyridine rings in the hydrazone mol-ecule is 7.12 (3)°. In the crystal structure, inter-molecular N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds link the hydrazone and water mol-ecules into double layers parallel to (101). The crystal packing exhibits weak π-π inter-actions between the pyrrole and pyridine rings of neighbouring hydrazone mol-ecules [centroid-centroid distance = 3.777 (3) Å]. The crystal studied was a non-merohedral twin, the refined ratio of twin domains being 0.73 (3):0.27 (3).