A simplified thermodynamic perturbation theory-dimer framework is used to derive air equation of state for hard-sphere chains. The accuracy of the equation is tested against simulation data for hard-sphere chains containing rtp to 201 hard-sphere segments, A comparison is also presented with the results of other more c sophisticated hard-sphere chain equations of state. The equation reproduces die compressibility factor of hard-sphere chains obtained from molecular simulation with a reasonable degree of accuracy. The equation cart potentially form the theoretical backbone of an equation of state for real chainlike molecules. From a practical perspective, if has the advantage of being considerably simpler than alternative hard-sphere chain equations.