The temperature effect on current gain is presented for InGaP/InGaAsN/GaAs heterojunction bipolar transistors (HBTs) including as-grown and annealed HBTs. The annealed HBT was annealed before device fabrication at 700°C for 30 sec. Experimental results showed that the current gains of the annealed HBT increase with the increase of temperature in the temperature range of-20-100°C. The smaller the collector current, the larger is the positive differential temperature coefficient. At high current levels, the current gain dependence on temperature is significantly reduced. On the other hand, a negative coefficient is observed in the as-grown HBT in all current range. This finding indicates that the annealed InGaP/lnGaAsN/GaAs HBT is better candidate than the as-grown InGaP/InGaAsN/GaAs HBT for power devices.