  The propagation of UHECRs is affected by the intergalactic magnetic fields
that were produced during the course of the large scale structure formation of
the universe. We adopt a novel model where the large scale extragalactic
magnetic fields (EGMF) are estimated from local dynamic properties of the gas
flows in hydrodynamic simulations of a concordance LambdaCDM universe. With the
model magnetic fields, we calculate the deflection angle, time delay and energy
spectrum of protons with E > 10^{19} eV that are injected at cosmological
sources and then travel through the large scale structure of the universe,
losing the energy due to interactions with the cosmic background radiation.
Implications of this study on the origin of UHECRs are discussed.
