  I report on work done with Tomislav Prokopec (Heidelberg, CERN). We computed
the one loop self-energy of a massless fermion during inflation. When the
fermion is free it experiences only a small amount of inflationary particle
production owing to the conformal invariance of its classical action. However,
when the fermion is Yukawa coupled to a massless, minimally coupled scalar,
there is copious production of fermions. In a more complicated model this
effect might generate baryon asymmetry during inflation.
