The ratio of inclusive spectra of neutrons and protons in antiproton-, pion-, and proton-nucleus interactions at intermediate energies has been considered in the framework of the intranuclear cascade (INC) model. The ratio predicted by the standard INC model is consistent with the experimental data for pion- and proton-induced reactions, but contradicts the ratio obtained in antiproton-nucleus annihilation measurements. It has been shown that for pion-nucleus interactions the n/p ratio is much affected by isotopic effects in pion absorption and mainly depends on pion charge. Nevertheless, due to the presence of positive, negative, and neutral pions in antiproton-nucleon annihilation the calculated n/p ratio becomes close to the N/Z ratio of the target nucleus. The coalescence of nucleons, preequilibrium emission of particles, interaction of annihilation pions with the nuclear Coulomb field, neutron halo effects, and many body annihilation have been considered as possible candidates which would affect the n/p ratio in antiproton-nucleus annihilation. A simple quark counting estimation for the n/p ratio in many body annihilation has been made.