In order to described the behaviour of fluids, the generalized van der Waals theory has been utilized as a starting point to combine different repulsive and attractive terms. An example is the work of Tavares and Rajagopal (1992) who proposed an equation of state based on the lattice gas model. Using the attractive term of this equation, the performance of several expressions for the repulsive term in the generation of equations of state is compared in this work. Such a comparison is based on the calculation of vapour-liquid equilibria of pure fluids. The following reference terms were considered : the hard-sphere model of Carnahan and Starling (1969); the chain of rotators proposed by Chien et al. (1986); the hard convex body model suggested by Boublik (1975); the Guggenheim-Staverman approach (Staverman, 1950) as used by Tavares and Rajagopal (1992). The selected equation of state, which uses the Guggenheim-Staverman approach as reference term, is compared to the SPHCT model, to the Soave cubic equation, and to a modification of this equation proposed by Aznar and Telles (1992) in the correlation of the behaviour of several fluids, ranging from simple apolar molecules to chainlike polar substances; this proved to be the best option for describing the vapour-liquid equilibria.