Computations based on Large Eddy Simulation(LES) with and without inflow turbulence are applied to the flowfield around a high-rise building model. The results are compared with those of the experiments and a revised k-ε model in order to clarify the effect of the velocity fluctuations at the inflow boundary on the prediction accuracy of time-averaged velocity fields around the building. Special attention is paid to the prediction accuracy for reproducing the flow behind the building. The results of the LES with inflow turbulence showed generally good agreement with experiment in terms of the distributions of velocity and turbulence energy in this region. This improvement results mainly fom the fact that the periodic velocity fluctuation behind the building is well reproduced in this case.