For helium-4, we present ab initio, semiclassical calculations of virial coefficients B-n for n = 2, 3, 4, and 5 from 50 to 1000 K. Using our values of B-4 and B-5 and the more accurate literature values of B-2 and B-3, we argue that the ab initio virial equation of state is more accurate than recent, high-quality, densimeter measurements spanning the range {223 K < T < 500 K, p < 38 MPa}. Thus, the present values of B-4 and B-5 extend the useful temperature and density range of ab initio helium standards. (C) 2012 Elsevier B.V. All rights reserved.