  We compute the CP violating decay asymmetries relevant for baryogenesis
scenarios involving the out of equilibrium decays of heavy particles, including
the finite temperature effects arising from the background of light thermal
particles which are present during the decay epoch. Thermal effects can modify
the size of CP violation by a sizeable fraction in the decay of scalar
particles, but we find interesting cancellations in the thermal corrections
affecting the asymmetries in the decays of fermions, as well as in the decay of
scalars in supersymmetric theories. We also estimate the effects which arise
from the motion of the decaying particles with respect to the background
plasma.
