Molecular dynamics results of pressure and potential energy for the reference system of the Weeks-Chandler-Andersen theory applied to two-dimensional fluids have been obtained in a wide range of temperatures and densities. These results are used to test the validity of six different analytical equations of state for hard-disk fluids proposed in the literature (some of which have been published recently), together with two different analytical expressions for the molecular diameter, to describe the properties of the above-mentioned fluids. The best choices for the combination of equations of state and molecular diameters in the calculation of the pressure and potential energy are given. It is shown how that choice may differ for different ranges of temperatures and densities, and how there is not a direct relation between the simplicity or complexity of the analytical expressions and their accuracy. (C) 1997 American Institute of Physics. [S0021-9606(97)50441-7].