  In a minimal model of leptogenesis, the observed baryon asymmetry is realized
after high-scale reheating into the lightest sterile neutrino. We consider
constraints on this scenario from the stability of the Higgs vacuum during
pre-heating. Depending on the reheat temperature, the lightest sterile neutrino
may be in or out of thermal equilibrium at production. Demanding stability of
the Higgs vacuum during pre-heating, we find strong constraints which primarily
impact the parameter space of thermal leptogenesis.
