The effect of hard-sphere-chain equations on the description of phase behavior is presented by the comparison of perturbed hard-sphere-chain (PHSC) theory with statistical associating fluid theory (SAFT) for square-well fluids. The PHSC-type equation of this work is based on the hard-sphere-chain equation of Chiew (PY-CS), the square-well fluid model of Alder et al., and the expression of Chen and Kreglewski. The PHSC-type equation has expressions similar to those of the SAFT equation. A comparison of the PHSC-type equation with the SAFT model shows that the PHSC-type equation of state presents slightly better results of pure compounds and much better vapor-liquid equilibrium results of high-concentration polymer solutions.