The dependence of the absorption coefficient a on the photon energy is investigated for different degenerately doped samples of n-type GaSb in the region of the fundamental absorption. A comparison of the experimental data with the theory by Dyakonov e t al.shows satisfactory agreement for a > 500 crn-'. The application of pulsed electric fields a t a lattice temperature of 6 K gradually removes the Burstein-Moss shift.