The virial equation of state up to fourth order for Argon is constructed using highly accurate ab initio two-and three-body potentials. Experimental EOS data is reproduced within at least +/-1.7% in terms of pressure near the critical point and significantly better for larger volumes (less than +/- 0.5% or +/- 0.025 MPa for 200 cm(3) mol(-1) or larger). The critical temperature of T-c = 148.8 K obtained for the liquid-vapor phase equilibrium is in excellent agreement with the experimental value of 150.687 K. (C) 2011 Elsevier B. V. All rights reserved.