The effect of the Mn3+ ion on the local distortions of the FeO6 octahedra in orthoferrite samples was investigated. Mössbauer spectroscopy measurements for a series of the HoFe1−xMnxO3 (x=0.0−0.7) orthoferrite samples with space group Pnma was carried out at temperatures above the Néel point (700 K). The electric field gradient (EFG) tensor on Fe ions for these compounds was found using the first-principle calculations. The concentration dependence of the quadrupole splitting was resulted from the experimental and theoretical data. The absence of an electron contribution to the quadrupole splitting at all the manganese concentrations was demonstrated. It was shown by the theoretical calculations that the values of all the electric field gradient components increase significantly with the manganese concentration in the system, and the eigenvectors Vxx and Vyy of the electric field gradient tensor sharply change their direction at concentrations of x > 0.1.