Curcumin, a polyphenolic yellow pigment found in turmeric, is commonly used as a coloring agent in foods, drugs, and cosmetics. In our previous study, we found that low levels of curcumin did not increase the reactive oxygen species (ROS) formation and caused no damage to DNA in human hepatoma G2 (HepG2) cells, but at high doses, curcumin imposed oxidative stress and damaged DNA. In the present study, we are determined to investigate the genotoxic and antigenotoxic effects of curcumin using HepG2 cell line, a relevant in vitro model to detect the cytoprotective, antigenotoxic, and cogenotoxic agents. The results of micronucleus (MN) assays showed that, on one hand, curcumin at the high tested concentrations (8 and 16 microg/ml) displayed a small but significant increase in the frequency of MN, and on the other hand, it was observed that the low tested concentration (2 microg/ml) significantly reduced the MN formation induced by the chemotherapeutic agent cyclophosphamide. The present results indicate that curcumin shows both genotoxicity and antigenotoxicity depending on its concentration.