  In a left-right symmetric model, with the scalar sector consisting of several
bi-doublets and two doublets, neutrinos remain as Dirac fermions in all order
in perturbation theory. Although with only two bi-doublets the neutrino masses
need still a fine tuning, this is not the case when a third bi-doublet is
added. One of the scalar doublet may be of the inert type since it is protected
by the left-right symmetry.
