In this research, the genotoxic effects of Pinelliae Rhizoma (PR) extracts, one of famous herbal agents in Korean medicine were evaluated using the mouse micronucleus test. PR extracts was administered once a day for 2 continuous days by oral gavage to male ICR mice at doses of 2000, 1000, and 500 mg/kg. Cyclophosphamide was used as a known genotoxic agent in a positive control. The appearance of a micronucleus is used as an index for genotoxic potential. No PR extracts treatment-related abnormal clinical signs, body weight changes and mortalities were detected. Significant (p<0.01) increases of the numbers of polychromatic erythrocytes contain micronucleus in prepared bone marrow cells were detected in CPA and PR extracts 2000 mg/kg treated groups as compared with intact control, respectively. The results of intraperitoneal dose mouse bone marrow cell micronucleus test of PR extracts were positive in the present study. It is considered that there were no problems from cytotoxicity of PR extracts tested in this study because the polychromatic erythrocyte ratio was detected as > 0.42 in all tested groups.