The effect of high Gamma ray dose on two types of commercial transistors having different DC specifications has been investigated. The transistors were discrete N-JFETs intended as front-end component in nuclear read-out systems. They were exposed to different Gamma doses with a maximum of 10,000kGy. The irradiation influence was represented by the analysis of the DC and the induced noise characteristics.The results show that the noise was more sensitive to irradiation than the DC parameters, and the radiation effect depends on the original DC specifications. It was also found that the first dose induces noise more than the next doses. Similar effects were observed either if the irradiation is done by one single dose or by many successive accumulated doses.