The molecules of ethyl 5-amino-1-(4-cyanophenyl)-1H-imidazole-4-carboxylate, C13H12N4O2, are linked into a chain of alternating R(2)2(10) and R(4)4(34) rings by a combination of N-H...N and C-H...N hydrogen bonds. In ethyl 5-amino-1-(4-chlorophenyl)-1H-imidazole-4-carboxylate, C12H12ClN3O2, where the ethyl group is disordered over two sets of sites, a combination of N-H...O, N-H...N, C-H...N and C-H...pi(arene) hydrogen bonds links the molecules into complex sheets. Two intermolecular hydrogen bonds, one each of N-H...N and C-H...O types, link the molecules of ethyl 5-amino-1-(2,6-difluorophenyl)-1H-imidazole-4-carboxylate, C12H11F2N3O2, into a continuous three-dimensional framework structure.