  It has been suggested that cosmological gamma-ray bursts (GRBs) can produce
the observed flux and spectrum of cosmic rays at the highest energies. However,
recent observations indicate that the redshift distribution of GRBs most likely
follows that of the star formation rate in the universe, a rate which was much
higher at redshifts 1.5-2 than it is today. Thus, most GRBs are at high
redshifts. As a consequence, any cosmic rays emitted by these GRBs at energies
above 2-3 X 10^{19} eV would be strongly attenuated by interactions with the 3K
background radiation. If one assumes rough equality between the energy released
in 10^{-2} to 1 MeV photons and that released in 10^{20} eV cosmic rays, then
less than 10 per cent of the cosmic rays observed above 10^{20} eV can be
accounted for by GRBs.
