Abstract: Objective To investigate the protective effects of boric acid(BA)on cisplatin(CDDP)-induced nephr otoxicity in human emmbryo kidney 293 cells and its possible mechanism.Methods The effect of BA on CDDP-induced cytotoxicity was evaluated by MTT assay.Lipid peroxidation was deter mined by measurement of thiobarbituric acid-reactive substances(TBARS)for med during the decomposition of lipid hydroperox ides.Reduced glutathione(GSH)was assayed using a fluorescence spectrophotometer to deter mine the effect of BA on CDDP-induced GSH depletion.Results BA pretreatment allev iated the CDDP-induced cytotoxicity and the IC₅₀ values for 24h were significantly increased from(0.38±0.04) mmol/L to(0.87±0.10)mmol/L(P<0.05).BA inhibited the increase of MDA for mation and alleviated the decrease of GSH contents.Conclusion BA pretreatment can remar kably alleviate CDDP-induced cytotox icity in 293 cells.Antiox idation and scavenging of free radicals underlies the mechanism.