Objective To investigate the proliferative inhibition of lens epithelial cell (LEC) by arsenic trioxide (ATO) and rhizoma curcumae (RC), in order to provide scientific basis for pursuing safe and effective natural drugs to prevent and cure after cataract. Design Experimental study. Participants Cultured Bovine LEC in vitro. Methods Changes of cellular form were observed with microscope. Different concentration of ATO (2.5, 5, 10?mol/L) and RC(5, 10, 20mg/ml) were added to the proliferative LEC separately. The effects of proliferative inhibition by ATO and RC on the LEC were measured with methyl thia-zolyl tetrazolium (MTT) assay method after 72 hours incubation. Main Outcome Measures Cellular form, Absorbance. Results Under the microscope, good growth and quantity increase were found in proliferative control group. Slowing proliferation,poor growth, and few disintegration were observed in ATO group and RC group. MTT assay: Different concentration of ATO (2.5, 5, 10?mol/L)and RC(5, 10, 20mg/ml) can significantly inhibit the proliferation of LEC and these effects were dose dependent(P