It is shown that a low-order expansion in powers of density about a short-range reference system, called a perturbed virial expansion, is superior to the common virial expansion and provides a reasonably accurate estimate of both the critical temperature of simple fluids and results on thermodynamics of real gas over a wider range of densities/temperatures. The results are presented for three common van der Waals hard-core models (square-well, Yukawa, and Sutherland) and for the realistic Leonard-Jones fluid. (c) 2011 Elsevier B.V. All rights reserved.