The authors have calculated the gain-current characteristics of a 70 A In0.2Ga0.8As—GaAs strained layer quantum well laser assuming strictk-selection and including spectral broadening due to carrier–carrier interactions at high carrier densities. The broadening lifetime, which is dependent upon energy and carrier density, has been calculated from first principles using an intraband Auger-type process. The effect of both electron–electron and hole-hole scattering has been included in the calculation of this lifetime. The paper compares the effect on the gain-current characteristics of the energy dependent lifetime and of a constant lifetime of 10−13s used typically in other calculations.