Due  to the  null result of  the CHOOZ experiment,  the full three-family  mixing  of neutrinos  is  still  unestablished.  In  the forthcoming years  several neutrino oscillation  experiments will test
this  full  mixing  scenario  trying   to  measure  the  size  of  the $theta_{13}$ angle  of the leptonic mixing  matrix.  Eventually, their outcome will  determine the  strategy to observe  CP violation  in the
leptonic  sector.

This  presentation  will focus  on  the status  and perspectives  for the experimental  determination of  $theta_{13}$. We also try  to anticipate what will be  our knowledge at the  end of the
CNGS  physics  programme  and  describe in  details  the  experimental techniques employed by ICARUS, MINOS  and OPERA to improve the present CHOOZ limit.