The protective effect of Agrimonia pilosa var. (AP) extract on potassium dichromate (K2Cr2O7)induced cytotoxicity in cultured NIH3T3 fibroblasts, was examined by performing an XTT assay for the cell viability and antioxidative effects, such as lactate dehydrogenase (LDH) activity and superoxide anion-radical (SAR) scavenging activity. In this study, K2Cr2O7 decreased the cell viability significantly in a dose-dependent manner, and the XTT50 value was determined to be 37.5 M, which was highly-toxic according to the Borenfreund and Puerner' toxic criteria. The antioxidant, butylated hydroxytoluene (BHT), increased remarkably the cell viability damaged by K2Cr2O7-induced cytotoxicity in these cultures. With regard to the protective effect of the AP extract on K2Cr2O7-induced cytotoxicity, AP extract produced a significant increase in cell viability and antioxidative effects as the inhibitory ability LDH and SAR scavenging ability. These findings suggest that oxidative stress is involved in the cytotoxicity of K2Cr2O7, and the AP extract effectively protected the cells from K2Cr2O7-induced cytotoxicity by antioxidative effects. These results suggest that natural resources, such as AP extract, may be a putative therapeutic agent for the diminution or treatment of cytotoxicity induced by heavy metallic bases, such as K2Cr2O7 correlated with oxidative stress.