  The creation of large scale magnetic fields is studied in an inflationary
universe where electrodynamics is assumed to be nonlinear. After inflation ends
electrodynamics becomes linear and thus the description of reheating and the
subsequent radiation dominated stage are unaltered. The nonlinear regime of
electrodynamics is described by lagrangians having a power law dependence on
one of the invariants of the electromagnetic field. It is found that there is a
range of parameters for which primordial magnetic fields of cosmologically
interesting strengths can be created.
