For a long time Rhus vemiciflua Stokes (RVS) has been traditionally used as a herbal plant in Asia. In this study, we have investigated the effect of acetone extract of Rhus verniciflua Stokes (RVSE) and fisetin, a component of RVSE, on DNA damage response in NIH3T3 cells. Exposure of cells to DVB light $(200 J/m^2)$ and postincubation in growth medium for 48 hr resulted in a decrease of cell viability to about $10-20\%$ of nontreated control. Addition of various concentrations of RVSE in the postincubation medium, however, significantly increased the cell viability as compared with the values expected. The genotoxicity-decreasing effect was also demonstrated in cells exposed to UVB light and incubated in medium containing fisetin. The genotoxicity-decreasing effect of RVSE and fisetin was further demonstrated by various analyses including cell morphology studies, trypan blue exclusion assay and DAPI staining. By Annexin V binding analysis, RVSE and fisetin were shown to decrease the early apoptosis induced by UVB exposure. These results suggest the RVSE contain components that either increase the DNA repair or decrease the apoptosis in UVB-exposed cells.