  We discuss the possibility that, besides the usual gravitational lensing,
there may exist a sort of gravitational waveguiding in cosmology which could
explain some anomalous phenomena which cannot be understood by the current
gravitational lensing models as the existence of "brothers" objects having
different brilliancy but similar spectra and redshifts posed on the sky with
large angular distance. Furthermore, such a phenomena could explain the huge
luminosities coming from quasars using the cosmological structures as
selfoc-type or planar waveguide. We describe the gravitational waveguide theory
and then we discuss possible realizations in cosmology.
