This study aimed to evaluate the aqueous extract of Quercus infectoria galls extract (QIGE) as anticlastogenic. The effect of QIGE was tested in mice (5 groups for each test) treated with 7, 12-dimethylbenz (a) anthracene (DMBA), the strong sitespecific carcinogenic agent. In this study, the QIGE show no signs of toxicity, a single dose of DMBA (50 mg/kg) was injected intraperitoneally to Swiss albino mice caused a great increase in number of chromosomal aberrations, micronucleated polychromatic erythrocytes (MnPCEs) and reduction in the percentage of mitotic index (MI) (cytogenetic markers). Oral pretreatment and post-treatment of QIGE for 14 days at dose 2 gm/kg b.w. daily to DMBA-treated animals greatly reduced in number of micronucleus formation, chromosomal abnormalities such as chromosomal break, chromatid breaks, ring chromosome, dicentric chromosome and fragments. Besides, mitotic index frequency increased comparing with the positive control. The data suggest that QIGE has potent anti-clastogenic effect against DMBA-induced genotoxicity in bone marrow cells of albino male mice and it may have a protective effect against the mutagenicity of the polynuclear aromatic hydrocarbons (PAH).