In contrast to the condensation of pure vapours and vapour mixtures of miscible liquids, the condensation of vapour mixtures forming immiscible or only partly miscible condensates is still poorly understood. Models describing heat transfer in the latter kind of condensation deviate so much from one another, not only quantitatively but also qualitatively, that reliable design of condensers is impossible. The reason lies primarily in the variety of flow patterns of two-phase condensates, which range from pure droplet to pure film condensation. This paper surveys literature reports of the flow patterns and heat transfer occurring during condensation of vapour mixtures in the miscibility gap of their liquids. Qualitative knowledge in this condensation area is shown to be satisfactory. Several models have been proposed for heat transfer. However, the heat transfer coefficients obtained from these models differ too much from one another to allow one to choose the "best" correlation. Our own experiments with a eutectic benzene-water mixture on a vertical tube show that the calculation scheme proposed by Hoon and Burnside leads to acceptable results.