  We present a semiclassical theory of shot noise in diffusive superconductor -
normal metal contacts. At subgap voltages, we reproduce the doubling of shot
noise with respect to conventional normal-metal contacts, which is interpreted
in terms of an energy balance of electrons. Above the gap, the voltage
dependence of the noise crosses over to the standard one with a
voltage-independent excess noise. The semiclassical description of noise leads
to correlations between currents at different electrodes of multiterminal SN
contacts which are always of fermionic type, i.e. negative. Using a quantum
extension of the Boltzmann - Langevin method, we reproduce the peculiarity of
noise at the Josephson frequency and obtain an analytical frequency dependence
of noise at above-gap voltages.
