  UHECRs are roughly isotropic and attain very large energies, $E \gtrsim
3\times 10^{20} \; eV$. Conventional models fail to explain both facts. I show
here that acceleration of UHECRs in GRBs satisfies both observational
constraints. Using M\'esz\'aros and Rees' (1994) model of GRBs as due to
hyperrelativistic shocks, I show that the highest energies that can be attained
thusly are $E\simeq 10^{20}\;\theta^{-5/3} n_1^{-5/6}\; eV$, explaining the
energy of the Bird \etal\/ (1995) event even without beaming. The traditional
photopion catastrophe affecting UHECR acceleration in AGNs is circumvented. An
order of magnitude estimate shows that the total energy flux of UHECRs at the
Earth is also correctly reproduced. A test of the model based upon the UHECRs'
distribution upon the plane of the sky is briefly discussed.
