  String/ M-theory compactifications predict the existence of a modulus field
with a mass of 100-10000 TeV. Its decay at MeV-temperatures generates large
amounts of entropy and washes out any previously produced baryon asymmetry. We
describe how the baryon asymmetry can be (re)generated by the modulus decay.
The mechanism relates the smallness of the asymmetry to the hierarchy between
the Planck- and the Fermi-scale.
