  Many neutrino mass models postulate the existence of at least two extra
fermions in order to account for the measured solar and atmospheric mass
splittings. In these models, however, the predicted hierarchy between the two
mass splittings is generically much larger than the observed one, unless extra
flavor symmetries are introduced. We present in this letter a radiative
neutrino mass model consisting of the Standard Model extended by one heavy
fermionic singlet and two scalars which predicts, under very general
conditions, a neutrino mass hierarchy in qualitative agreement with the
experimental value.
