  The origin of observed extremely high energy cosmic rays remains an
astrophysical enigma. We show that a single evaporating primordial black hole
should produce 8.5*10^14 particles over a 10^20 eV threshold. This emission
results from direct production of fundamental constituants and from
hadronization of quarks and gluons. The induced flux on the Earth is studied as
a function of the local density of exploding black holes and compared with
experimental data. The discovery potential of future detectors is finally
reviewed.
