The genotoxic effects of antimicrobial food additive sodium sorbate (SS) was assessed by using chromosome aberrations (CAs), sister-chromatid exchanges (SCEs), and micronucleus (MN) in cultured human lymphocytes and comet assay in isolated human lymphocytes. Lymphocytes were treated with four concentrations (100, 200, 400 and 800 mu g/ml) of SS as well as a negative (sterile distilled water) and a positive control (Mitomycin-C: MMC for cultured lymphocytes and H2O2 for isolated lymphocytes). The result of this study indicated that SS increased the frequency of CAs at both 24 and 48 h period compared to control. When gaps were included, this increase was significant at 200, 400 and 800 mu g/ml concentrations at 24 h and, at all concentrations at 48 h treatment time. When gaps were excluded, this increase was significant at only 800 mu g/ml concentration at both 24 and 48 h treatments. In addition, SS increased SCEs/cell and MN frequency at 400 and 800 mu g/ml concentrations at both 24 and 48 h compared to negative control. Furthermore, this additive caused DNA damage at all concentrations in isolated human lymphocytes after 1 h in vitro exposure. The present results show that SS is genotoxic to the human peripheral blood lymphocytes in vitro at the highest concentrations.