The influence of [sub 60]Co γ radiation on the current-voltage characteristics of high electron mobility transistors is examined in the dose range from 1 × 10[sup 4] to 6 × 10[sup 8] R. No changes are observed up to a total dose of 1 × 10[sup 7] R, but radiation-induced degradation of the transistors occurs when the dose exceeds 1 × 10[sup 8] R. The possible causes of the effects observed are discussed.