The NPN transistors were irradiated with 80 MeV Nitrogen ion in the dose range from 100 krad(Si) to 100 Mrad(Si). The different electrical characteristics like Gummel characteristics, current gain (hFE) and output characteristics( IC-VCE) were studied before and after irradiation. After nitrogen ion irradiation a significant increase has been observed in the collector current (IC) along with increase in base current (IB). The hFE of the transistors decreased drastically after ion irradiation. Moreover, the output charact eristics of the irradiated transistor show that the collector current (IC) in the saturation region (ICsat) decrease with increase in the ion dose.