A new equation of state for hard chain moleculesThe formerly proposed equation of state of fused hard-sphere molecules is applied to evaluate the compressibility factor of systems of flexible chains. A fair agreement with the available Monte Carlo data is obtained. Next, the equation of state extended to mixtures is used to predict the P-V-Tbehavior of binary systems composed of simple hard-body chains differing in the number of atoms in molecules. Good accordance of the calculated and pseudoexperimental values-within the experimental errors of the data-is obtained. To get further experimental data for pure chain molecules and their mixtures Monte Carlo simulations were performed for the system of linear tetraatomic molecules with the site-site length 1 * = 1 and their equimolar mixtures with hard dumbbells at several densities.Comparison of the results for the linear tetraatomics with data on the corresponding flexible chain molecule system reveals a good agreement of the data. The proposed equation of state describes adequately the behavior of both the pure fluid and mixtures.