Changes in the crystalline structure of silk sericin and fibroin induced by gamma-irradiation is described. Sericin remained unchanged, but the decomposition temperature decreased. Silk type crystal of fibroin in the solid state changed into silk II type when the dose exceeded 4.6 Mrad. No changes with silk II type crystal. See also preceding abstract for related discussion (AATA Vol. 23, Abstract No. 1116, PAR No. 33795). -- AATA