Abstract: To discuss the mutagenesis and anti-mutagenesis effects of juglans mandshurica maxim extract (JMME) and to evaluate whether juglans mandshurica is genotoxic or not. METHODS：To choose 80 KM mice，and randomly grouped negative control group， positive control group (CP，0.04 g/kg)， water extract groups with different dose JMME (6.55，13.09，26.18 g/kg，1/8，1/4，1/2 LD50 )， and antimutagenicity groups with different dose JMME water extract and CP (0.04 g/kg). There were 8 groups with 10 mice each group. Test whether the JMME had genotoxicity and anti-mutagenic effect， marrow micronuclei test was carried out. RESULTS： The micronucleus incidence of negative control group was 2.65‰， and that of positive control group was 28.82 ‰ (P<0.01). But there were little statistical differences (P>0.05) between the water extract groups with different doses JMME and the negative control group. Comparing the antimutagenicity groups with the positive control group， the low dose (6.55 g/kg) group showed no statistical significance (P>0.05)， but both the intermediate dose (12.09 g/kg) group and the high dose (26.18 g/kg) group had significant difference (P<0.05)， and the high dose group was lower than the intermediate group (P<0.05). CONCLUSION：Under our experimental conditions，JMME had no genotoxicity. For the micronucleus incidence induced by CP， it had some dose-dependent anti-mutagenesis effect.

Key words: juglans mandshurica maxim extract, genetoxic, mutagenesis, anti-mutagenesis