A high concentration of the acceptor impurities (NA about of 1020 cm−3) influence on the electronic structure, the Fermi level location, electro-conductivity, Seebeck coefficient, and magnetic susceptibility in the n-ZrNiSn intermetallic semiconductors was investigated. An importance of both donor and acceptor impurity bands in the heavy-doped n-ZrNiSn conductivity was determined. A transition of the conductivity from an activated- to the metallic-like type, with acceptor impurities concentration changing, was observed.