In this study, gamma radiation was applied between 10-120 Gy at 10 dose levels for 2-4 days-old pupae; 10-150 Gy at 11 dose levels for 12-14 days-old adults of T. confusum. All experiments were carried out in incubators maintained at 27+/-0.5 degrees C and 70+/-5% relative humidity. The development of adults reared on different flours from irradiated pupae was not prevented by exposing these stages investigated doses. Rapidly developing confused flour beetle were more susceptible to killing by gamma radiation. Adults that emerged from treated pupa had elytral and other deformities. In barley flour, rate of deformed individuals were higher than the other rearing media. LD(50), LD(99,9) and SD99,9 values for wheat flour were high compared with both barley and maize flour. For adult treatment, there were differences in survival among rearing diets especially at doses of 40, 50 and 60 Gys. But there were no differences for LD(50) and LD(99,9) values at adult stage, indicating little influence of rearing medium on susceptibility of adults. On the other hand, there were little differences between rearing diets for SD50 and SD99,9.