The widespread application of collagen warrants studies on the effects of ultraviolet (UV) radiation on stabilized collagen. The negative impact of UV radiation is well known. Because collagen is used as a biomaterial in various biomedical applications, knowing the effects of UV irradiation on stabilized collagen has become essential. In this study, the effects of UV irradiation on collagen stabilized with green tea polyphenols, that is, Acacia mearnsii (wattle), and catechin has been studied. The fluorescence intensity has been found to decrease with irradiation for native and wattle-treated collagen. Spectral studies have indicated that the photo-degradation products increase after irradiation for native collagen, whereas collagen treated with catechin or A. mearnsii exhibits different responses depending on the duration of the irradiation. The duration of the irradiation has a significant influence on polyphenol-treated collagen. (c) 2007 Wiley Periodicals, Inc.