An investigation into the effects of temperature on degradation mechanisms in GaAs/GaAlAs DH lasers has been carried out. A mechanism (or mechanisms) independent of stimulated light levels is found to be relatively insensitive to temperature. This suggests that a residual failure mechanism may be associated with defect motion being enhanced by nonradiative recombination. A statistical analysis of the lifetest results and photoluminescence studies of lifetested devices suggest that there may be different mechanisms in operation at different temperatures. Thus, great care must be exercised before using conventional extrapolation techniques to predict laser lives at room temperature.