The effects of low doses of gamma irradiationoncotton, Gossypium barbadence kidney beans, Phasolus vulgaris were investigated. Seeds for each crop were irradiated with 4 doses of gamma radiation, 15, 25, 35 and 45 Kilo rad for cotton and 5, 10, 20and 30 Kilo rad for kidney beans. Plants of the two crops were used to determine growth parameter. Since,  kidney beans plants were negatively affected in the most of its growth parameter as a result of gamma radiation, and cotton plants were highly affected and clearly activated, therefore, the effects  of  gamma radiation on phenolic compounds and plant tolerance to pests were took place on cotton plants only. Increasing radiation dose obtained increase in number of phenolic compounds; eight different phenolic plants were detected in irradiated cotton plants. Feeding Spodoptera littoralis (Boisd.) larvae on irradiated cotton leaf, induced larval mortality with 100, 100, 73.3 and 85 % for the 15, 25, 35 and 45 Kilo rad treatments, respectively, compared with 20% for the larvae feed on control plants. On the other hand, irradiated cotton plants attract aphids compared with its abundance on control plants.