The purpose of this investigation is to examine the effect of numerical viscosity in finite difference flow analysis. In order to solve high-Reynolds-number flow, the 3rd-order upwind scheme is commonly used. However, computation by the 3rd-order scheme is sometimes inadequate by its numerical viscosity. In this paper, the 5th-order upwind and modified 4th-order upwind schemes are applied to the convective term in the Navier-Stokes equations. The comparisons are made in a two-dimensional driven cavity flow problem for various ranges of Reynolds numbers. The effects of grid density and numerical viscosity on the accuracy of the numerical results are included. Comparison of the computed results with Ghia's data shows that velocity on the centerline of the square cavity are simulated well when using the 5th-order upwind and modified 4th-order upwind schemes. The results indicate the importance of the numerical viscosity at high Reynolds numbers.