  We formulate a statistical model for description of nuclear composition and
equation of state of stellar matter at subnuclear densities and temperature up
to 20 MeV, which are expected during the collapse and explosion of massive
stars. The model includes nuclear, electromagnetic and weak interactions
between all kinds of particles, under condition of statistical equilibrium. We
emphasize importance of realistic description of the nuclear composition for
understanding stellar dynamics and nucleosynthesis. It is demonstrated that the
experience accumulated in studies of nuclear multifragmentation reactions can
be used for better modelling properties of stellar medium.
