The coexisting densities and vapor pressures of R143 (1,1,2-trifluoroethane) have been measured at NIST from 314 to 401 K. These results were compared with available R143 data. The critical point was not determined experimentally because of the temperature limitations of the apparatus. However, a revised estimate of the critical point based on the new experimental data was obtained by combining a new method of critical temperature estimation with a previously reported method of critical density determination. These data and the data of others were represented by both the Carnahan-Starling-DeSantis equation of state and the Deiters equation of state. The Carnahan-Starling-DeSantis equation of state better represented the data and is easier to use for the calculation of the thermodynamic properties of R143.