  It is known that the charged lepton masses obey to high precision an
interesting empirical relation (Koide relation). In turn, the light neutrino
masses cannot obey such a relation. We note that if neutrinos acquire their
mass via the seesaw mechanism, the empirical mass relation could hold for the
masses in the Dirac and/or heavy Majorana mass matrix. Examples for the
phenomenological consequences are provided. We furthermore modify the mass
relation for light neutrino masses including their Majorana phases, and show
that it can be fulfilled in this case as well, with interesting predictions for
neutrinoless double beta decay. Finally, we remark that while the relation does
not hold for the up- and down-quarks, it may be valid for the u, d, s quarks,
and for the c, b, t quarks.
