A method is described to incorporate the Ewald lattice-sum method into quantum mechanical calculations in hybrid quantum and molecular mechanical (QM/MM) fluid simulations. The procedure is illustrated through standard free energy perturbation calculations in the context of Monte Carlo simulations. The free energy of hydration of chloride ion was computed using the hybrid QM/MM-Ewald method, and comparison was made to results obtained with standard spherical cutoff, The results indicate that the hybrid QM/MM-Ewald method can be effectively used to include long-range electrostatic interactions in quantum mechanical calculations of condensed media.