  We discuss the question of CP-violation in the effective Hamiltonian approach
in models of leptogenesis through heavy right handed neutrino decays. We first
formulate the problem in four component notation and then point out that before
the heavy neutrinos have decayed away, the universe becomes CP-asymmetric in
the heavy neutrinos. However, the lepton asymmetry generated after they
completely decay are independent of this asymmetry.
