  We study the dependence of the M_bh - M_host relation on the redshift up to
z=3 for a sample of 96 quasars the host galaxy luminosities of which are known.
Black hole masses were estimated assuming virial equilibrium in the broad line
regions (Paper I), while the host galaxy masses were inferred from their
luminosities. With this data we are able to pin down the redshift dependence of
the M_bh - M_host relation along 85 per cent of the Universe age. We show that,
in the sampled redshift range, the M_bh - L_host relation remains nearly
unchanged. Once we take into account the aging of the stellar population, we
find that the M_bh / M_host ratio (Gamma) increases by a factor ~7 from z=0 to
z=3. We show that Gamma evolves with z regardless of the radio loudness and of
the quasar luminosity. We propose that most massive black holes, living their
quasar phase at high-redshift, become extremely rare objects in host galaxies
of similar mass in the Local Universe.
