[en] The polyphenol trans-resveratrol (trans-3, 4',5-trihydroxystilbene) is a natural phytoalexin, reported to exert different biological activities, such as antioxidant properties. In the attempt to make possible the topic administration of resveratrol it will be immobilized in a hydrogel matrix obtained by gamma radiation crosslinking process which can cause undesirable hydrolysis reactions in the active compound. The aim of this work was to verify the aqueous/ethanol resveratrol solution stability and antioxidant activity after irradiation at 20 kGy. The integrity and stability were compared with nature one by High Performance Liquid Chromatography (HPLC) technique. The antioxidant activity was determined by the free radical scavenging method, using 2,2-Diphenyl-1-picrylhydrazyl (DPPH.) as free radical. The results demonstrated the decomposition of resveratrol and reduction of antioxidant capacity after irradiation at 20 kGy dose. (author)