Long term and repeated exposure of UV light on the skin often induces chronic skin diseases such as skin cancer as well as photoaging, and the mechanisms of these skin damages are closely associated with up-regulation of matrix metalloproteinase's (MMPs) activities. We investigated the effect of 2′,4′,7-trihydroxyisoflavone purified from the whole plants of Viola hondoensis W. BECKER et H BOISSIEU (Violaceae) on the expression of MMPs in UV-B irradiated old aged human skin fibroblasts. 2′,4′,7-trihydroxyisoflavone markedly reduced UV-induced MMP-1 expression, but not MMP-2, at the both mRNA and protein levels in a dose-dependent manner. Our report is the first description for the ability of 2′,4′,7-trihydroxyisoflavone to regulate MMP-1 expression from ultraviolet-B irradiated primary cultured old aged human skin fibroblasts.