Molecules of 8-methyl-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C21H17N3, (I), are linked into cyclic centrosymmetric dimers by means of paired C-H...N hydrogen bonds. In each of 8-methyl-7,10-diphenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C27H21N3, (II), and 8-methyl-7-(4-methylphenyl)-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C28H23N3, (III), the molecules are linked by C-H...pi(arene) hydrogen bonds into sheets, although the detailed construction of the sheets is entirely different in (II) and (III). The molecules of 7-(4-methoxyphenyl)-8-methyl-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C28H23N3O, (IV), are linked into a complex three-dimensional framework structure by a combination of C-H...N, C-H...O and three independent C-H...pi(arene) hydrogen bonds.