The aim of the paper is to evaluate neutron shielding efficiency of ordinary concrete, heavy-weight concrete and geopolymer concrete modified with epoxy additive. Evaluation was based on neutron shielding efficiency calculations. Since the commonly used fast neutron effective removal cross-section calculation does not take into account thermal neutron absorption reactions, a method adopted from the fast neutron effective removal cross-section calculation based on the macroscopic cross-section calculation for compositions is therefore applied. The results confirmed that an efficient neutron shield requires a balanced mixture of light and heavy nuclei and polymer modification is a proper way for increasing neutron shielding efficiency.