Radiation induced primary radicals from dried pork myosin irradiated at 77 K, and the subsequent radicals appeared in the course of variable temperature elevation from 77 K to 313 K have been studied by ESR. The ESR spectram shows that the primary carbonyl anion radical in the peptide chain (g=2.0037) is the predominant transient product from the myosin irradiated at 77 K and somewhat higher temperature than 77 K. Then at 223 K, the secondary transient species, α-carbon radical on the peptide backon which was characterized by the ESR spectrum of the myosin just appeared via the variable elevation of temperature. Finally, this kind of radical decayed rapidly with elevating from 223 K to 313 K variably.