The molecular coordination numbers in the structures of sulfur and selenium polymorphs weredetermined by the method of VoronoiDirichlet polyhedra; the coordination number 14 was found to predominate. The obtained molecular coordination numbers were compared with those determined with the use of the van der Waals radii. It was shown that the special features of the topology of the environment of a molecule could be determined by analyzing the VoronoiDirichlet polyhedron of the molecular center of gravity. The pre-dominant polyhedron of this type was found to be the Fedorov cuboctahedron corresponding to the arrangement of the centers of gravity of molecules in sites of body-centered cubic lattices. Changes in the characteristics of interatomic contacts in the structures of selenium and tellurium polymorphs under increased pressure are considered.