Natamycin (pimaricin) (E235) is an antifungal that can be used as an antibiotic to treat most fungus infections. It has been globally used in a variety of foods and beverages. In the present study, the effects of natamycin on chromosome aberrations (CAs), sister chromatid exchanges (SCEs), and micronucleus (MN) formation in human lymphocytes cells were investigated. The human lymphocytes were treated with 13,18, 23, and 28 mu g/mL of natamycin for 24 and 48 h. Natamycin induced the SCE frequency at the highest concentration for 48 h only; however, it induced the structural CA and MN frequency at all concentrations when compared to control and at all concentrations, except the lowest concentration (13 mu g/mL), when compared to solvent control. Natamycin showed a cytotoxic effect by decreasing the replication index, mitotic index, and nuclear division index (NDI), especially at the highest concentrations for two treatment periods.