Abstract: Abstract: Objective To explore the damage effect of ochratoxin A (OTA) on chromosome of human gastric epithelium cells (GES-1) in vitro. Methods The situation of chromosome damage was evaluated by micronucleus test after different concentrations of OTA treatments(5, 10, 20 μmol/L) for 24 h. The type of chromosome aberration was further observed by chromosome karyotypic analysis after OTA treatment at different concentrations. Results The micronucleus test results showed that the micronucleus rates in 10 and 20 μmol/L OTA treatment groups were (2.90±0.54)% and (3.84±1.06)% respectively, which were signifi cantly higher than that in control group (1.23±0.27)%, P<0.05.Chromosome karyotypic analysis showed that total frequencies of aberrations were significant increased after OTA treatment. The total frequencies of aberrations were 14%, 20% and 24%, respectively in 5, 10 and 20 μmol/L OTA treated groups, which were all signifi cantly higher than that in control group (4%, P<0.05). Conclusion OTA could increase micronucleus rate and induce chromosome aberration in GES-1 cells.