A fundamental approach to the calculation of homogeneous azeotropes of multicomponent mixtures was published by Fidkowski et al. (1993) [Fidkowski et al., Computers Chem Engng 17, 1141 (1983)] recently. This paper is a generalization of that approach for cases where multiple liquid phases can coexist in equilibrium (heterogeneous azeotropes). An example for the mixture ethanol-water-cyclohexane-benzene is presented.