The conductance in metal - insulator - degenerate semiconductor tunnel junctions is obtained and analyzed. Regions of various shapes of the conductance are determined by use of two reduced parameters. For relatively light degeneracy and high barrier, a conductance minimum occurs at the Fermi energy. Otherwise, a minimum may occur at a voltage equal to or smaller than the Fermi energy and an additional pair of extrema may exist, depending on the type of the semiconductor and the nature of the insulator band edges in providing the tunneling barrier. © 1968 The American Institute of Physics.