Experimental tie-lines are presented for (cyclohexane + 2-propanol + aceto-nitrile), (cyclohexane + benzene + acetonitrile + methanol) and (cyclohexane + 2-propanol + acetonitrile + methanol) at 25-degrees-C. The experimental results have been well reproduced by using the extended UNIQUAC and modified Wilson models with binary, ternary and quaternary parameters obtained in fitting the models to literature and the present experimental data.