[en] Chicken meat with bone was irradiated by gamma rays at -19 - 10degC. Both amounts of hydrocarbons formed from fatty acids and intensity of ESR signals in bone fragments were measured. Very good correlation was found between the amount of hydrocarbons and the intensity of ESR signals. The amount of hydrocarbons (C_n-2:1), having 2 carbon atoms less than the original fatty acids and an additional double bond, was almost constant irrespective of the irradiation temperature. The amount of hydrocarbons (C_n-1:0), having 1 carbon atom less than the original fatty acids, increased as the irradiation temperature raised. As the ratio between corresponding fatty acids, the ratio between hydrocarbons (C_n-2:1) is a suitable index in the detection of the irradiation. On the contrary, the ratio of hydrocarbons from the same fatty acid, (C_n-2:1)/(C_n-1:0), varied according to the kind of fatty acid and irradiation temperature. It was found that under the irradiation temperature of -19 - 10degC, the intensity of ESR signals of bone is not affected by the irradiation temperature. (J.P.N.)