Abstract: Objective Fluorescent brightener is one of chemicals listed in "Classification Chart of Occupational Hazardous" announced by SAWS. In order to understand the mechanism of genetic damage, the chromosome damage induced by fluorescent brightener on CHL (Chinese hamster lung) cells was studied. Methods CHL cells were treated with different concentrations of fluorescent brightener 28 in vitro and chromosome aberration of treated CHL cells was detected. Results Under the testing conditions with an exogenous source of metabolic activation system(S9), there was no significant increasing percentage of cells with structural aberrations in treated groups, compared with negative control. Conclusion Fluorescent brightener 28 may not induce chromosome damage in cultured mammalian cells.