We present molecular-dynamics simulation results for the equation of state of one-component fluids containing freely jointed hard chains of lengths 2, 4, 8, 16 and 32, and compare these results with the predictions of the generalized Flory-dimer theory. In addition, we present the predictions of a modification to the generalized Flory-dimer theory which uses accurate values for the exclusion volumes of hard chains. Using a Monte Carlo integration technique, we obtain the conformationally averaged exclusion volumes, mean-squared radii of gyration and mean-squared end-to-end distances of isolated freely jointed hard chains of lengths 3, 4, 5, 6, 7, 8, 15, 16, 17, 31, 32, 33 and 64. This modification to the generalized Flory-dimer theory improves the agreement with simulation results for the longer chains at high densities, but has negligible effect at intermediate densities. © 1990 Taylor and Francis Ltd.