The theory of free-carrier absorption (FCA) of IR signals and of electron mobility in n-PbTe is developed, taking into account the anisotropic non-parabolic band structure and the corresponding wave function admixture. Computed values of both FCA and mobility are given for comparison with the available experimental results at 300 and 77 K. It is found that the experimental values of both FCA and mobility at 300 K may be fitted well with theory by choosing a value of 15 eV for the acoustic phonon deformation potential constant and a value of effective mass within 5% of the values reported earlier. For 77 K, the calculated value of FCA is close to the experimental value, but the values of mobility are about 1.5 times higher. These values may be made to agree with the experimental values only by choosing a value of effective mass which is 27% higher than the values obtained from magnetophonon experiments. © 1978.