Bianchi type I universe models with irreversible matter creation

The effects of matter creation on the evolution and dynamics of an anisotro pic Bianchi type I space-time is investigated in the framework of open ther modynamic systems theory. For a cosmological fluid obeying a Zel'dovich typ e equation of state (rho = p) and with particle creation rate proportional to the square of the mean Hubble function and to the energy density of matt er, respectively, the general solution of the gravitational field equations can be expressed in an exact parametric form. Generically all models start from a non-singular state. In the large time limit anisotropic cosmologica l models with particle creation rate proportional to the square of the Hubb le function end in an isotropic hat (inflationary or non-inflationary) phas e while models with particle source function proportional to the energy den sity of matter do not isotropize, ending in a Kasner-type geometry.