Background: Cassava leaf contains many kinds of flavonoids, most of flavonoids function as effective antioxidants in vivo. The protective effects of cassava (Manihot esculenta Crantz) leaf flavonoid extracts on liver damage were evaluated by carbon tetrachloride (CCl 4 )-induced injury in mice. Materials and methods: The protective effects of cassava leaf flavonoid extracts on liver damage were evaluated using CCl 4 -induced injury in mice. The mice were weighted to calculate sample quantity of mice. Bloods were taken to evaluate ALT and AST of serums. Livers were excised and weighted, and fixed for pathological observation. Prepared 10% liver tissue homogenate was used to evaluate MDA, SOD, GSH-PX levels. Results: Cassava leaf flavonoid extracts significantly decreased (p < 0.05) the relative liver weight when compared with the CCl 4 -treated group. The contents of ALT and AST in serum of experiment mice declined significantly when compared to those of the CCl 4 -treated group, but did not reach normal levels of control group. Pathological observation of livers showed that cassava leaf flavonoid extracts significantly ameliorated the CCl 4 -induced pathological changes. Conclusion These results provided biological evidence that cassava leaf flavonoid extracts indeed expressed potential efficacy of prohibiting liver injury in mice.