Objective To study the contents of MDA in host livers of sarcoma 180 -bearing mice after hypoxyradiotherapy. Methods The contents changes of MDA were studied in BALB/c sarcoma 180 -bearing mice by TBA method after breathing 10.5% oxygen during radiotherapy. The data were analyzed using SPSS software package. Results The contents of MDA were significantly lower in host livers in hypoxyradiotherapy group than those in the control group on the 7th and 14th day after radiotherapy. (P<0.05). Conclusion Hypoxyradiotherapy can decrease MDA contents in host livers and preserve normal tissues.