For systems with interatomic interactions that are well described by pairwise potentials, the pair correlation function provides a vehicle for passing information from the molecular-level to the macroscopic level of description. In this work, we present a complete demonstration of the use of the pair correlation function to simulate a fluid at the molecular and macroscopic levels. At the molecular-level, we describe a monatomic fluid using the Ornstein-Zernike integral equation theory closed with the Percus-Yevick approximation. At the macroscopic level, we perform a multiscale simulation with macroscopic evolution equations for the mass, momentum, temperature, and pair correlation function, using molecular-level simulation to provide the boundary conditions. We perform a self-consistency check by comparing the pair correlation function that evolved from the multiscale simulation with the one evaluated at the molecular-level; excellent agreement is achieved. (C) 2007 Elsevier B.V. All rights reserved.