  Neutrino data lead via the see-saw mechanism to masses of the right handed
neutrinos at the intermediate mass scale. Simple formalism is suggested which
incorporates the quark - lepton symmetry and allows one to find properties of
the intermediate scale (masses and mixing) from neutrino data. Averaged mass
scale and the mass hierarchy parameter are introduced and fixed by the data.
They determine natural ranges of masses and mixing at the intermediate scale.
In particular, scenario which includes the MSW solution of the solar neutrino
problem and tau neutrino as the hot component of Dark Matter of the Universe
leads to $M_2 = (2 - 4) \cdot 10^{10}$ GeV and $M_3 = (4 - 8) \cdot 10^{12}$
GeV in agreement with the linear mass hierarchy. Strong deviations from the
natural ranges imply fine tuning of parameters or/and certain symmetry of the
Majorana mass matrix of the right handed neutrinos.
