Isothermal (vapour + liquid) equilibria of (4-methylpentane-2-one + pyridine), (4-methylpentane-2-one + 1,4-dioxane), and (pyridine + 1,4-dioxane) have been measured at 308.65, 313.15, 318.15, and 323.15 K using the total-pressure method. The results are analysed by Barker's method with UNIQUAC, Wilson, and NRTL equations. All three models are found to represent the results satisfactorily. All mixtures show positive deviations from ideality; none forms an azeotrope. © 1989.