An extension of a volume-explicit equation of state for chains of tangent hard spheres to chains of fused hard spheres and their mixtures is presented. The extension was achieved by the use of a simple relationship between number of segments and nonsphericity parameter. A comparison of compressibility factors calculated using the extended equation with corresponding simulation data for hard dumbbell systems at various elongations and for fused long chains molecules and their mixtures has shown that the extended equation is reasonably accurate.