Transport properties ofn‐type germanium at 20 K have been calculated in the donor impurity range 1011–1014cm−3, for a constant electric field in the [111] direction. The mathematical treatment is based on Boltzmann's equation, taking account of acoustic phonon scattering and impurity scattering between the different valleys. The electron distribution function in each valley is approximated by a drifted Maxwellian. It is found that the threshold field for the onset of negative differential conductivity increases with increasing impurity concentration and the peak‐to‐valley ratio decreases significantly. The negative differential conductivity region ceases to exist for impurity concentrations larger than 4.5×1013cm−3.