Isochoric-, isobaric- and saturation-heat capacities are calculated from the modified Benedict-Webb-Rubin type equation of state (EOS) of Johnson et al. (1993) and from the van der Waals theory based EOS given by Mecke et al. (1995) for the Lennard-Jones fluid. The isochoric- and isobaric-heat capacities are also determined from NVT and NpT ensemble Monte Carlo simulations. A method is proposed for the determination of the saturation heat capacity using the appropriate fluctuation formulae in both ensembles. The EOS-based theoretical results show reasonable agreement with the simulation data. Comparing with real liquids the theoretical heat capacities based on EOSs, calculated along the vapour-liquid saturation curve, agree well with experimental data for argon and methane.