Abstract: ObjectiveTo investigate the antagonism of selenium on arsenic toxicity.MethodsMale Wistar rats were treated with arsenic trioxide and coadministration of arsenic trioxide and selenium compound.Clinical examinations included concentration of arsenic and selenium,hematology,biochemistry determination on blood and histopathologic examination.ResultsConcentration of arsenic in blood of coadministered group was significantly lower than that in arsenic poisoning group; Selenium at dose of 100μg/kg·bw can weaken some toxic effects of arsenic,such as decrease of erythrocyte count,hemoglobin contents and total concentration of hydrosulfide group in blood,spleen swelling,pathological damages to the liver,kidney and lung.ConclusionSelenium could promote the excretion of arsenic from blood,and antagonize toxicity of arsenic.