We derive a perturbation theory for linear and nonlinear molecules interacting through the Kihara potential. This theory may be considered as a simplified version of more elaborated treatments previously proposed for this model. An advantage of the new formulation is that expressions for Helmholtz free energy, pressure, and entropy are analytical so that vapor-liquid determination becomes an easy task. Vapor-liquid equilibria obtained from the theory showed fair agreement with simulation results of the model. Moreover, we compared theoretical predictions of coexistence densities and vapor pressures with experimental results for ethane, carbon dioxide, and benzene. Good agreement was found in al the cases over a broad range of temperatures. The presented treatment combines the simplicity required in chemical engineering applications with well-defined approximations on a statistical thermodynamic treatment.