Third virial coefficients of argon have been calculated using a recent ab initio state-of-the-art pair potentialand a new ab initio three-body potential. The theoretical results have been compared with experimental datain the range of temperatures from 130 to 673 K. The comparison reveals an excellent agreement between thetheoretical and the newest experimental results: For all considered temperatures, differences between thetheoretical and the experimental values are within uncertainties of the experimental data. The theoreticalthird virial coefficients reported in this work are also compared with those obtained using alternative theoreticalapproaches.