A major purpose of this investigation was to examine the degradation produced in silk by exposure to dry heat and to radiation from a xenon arc lamp. Degradation was assessed by measuring the breaking strength and the concentration of amino groups in the silk. Three additives were examined to determine whether they would retard the degradation: Wei To*h®*s #3 (a deacidifying agent), Goodrite*h®*s 3125 (an antioxidant), and Cyanox* h®*s 1790 (an antioxidant). The relationship between strength decrease and amino group increase is similar for both light and heat degradation. Based on the changes in breaking strength, the degradation by heat and light is of the first order. None of the three additives retarded the heat degradation as measured by breaking strength. In contrast, the two antioxidants did seem to retard the formation of amino groups. At this stage, general conclusions cannot be drawn regarding the effect of these agents on silk degradation.