Structure of two 4-aryl-1-trichloromethylisoquinolines, as well as 3-dichloromethyl-6-phenyl-1,2,4-triazine (a synthetic precursor of the corresponding isoquinolines), was studied by single crystal X-ray diffraction analysis. The effect of the nature of substituents in the heterocycles on their crystal structure was shown. The effect of acceptor di- and trichloromethyl groups on the nature of intermolecular interactions realized in crystals was demonstrated.