Abstract β-Caryophyllene is a bi-cyclic sesquiterpene that occurs in essential oils from several plants. A variety of biological activities have been ascribed to this compound. In particular, it seems to possess anti-carcinogenic properties, due to its capability to induce detoxifying enzymes or to enhance, in vitro and in vivo, the natural killer cell-induced cytotoxicity against tumours. Conversely, the knowledge on the DNA-damaging activity of the substance and its modulation is scanty. Therefore, in this study, we aimed at evaluating the capability of β-caryophyllene to protect cultured human lymphocytes from the genotoxic damage induced by ethyl methanesulfonate (EMS) and colcemid (COL) in the micronucleus assay. To investigate the mechanisms of action of this sesquiterpene, the cultures were treated with the compound before (pre-treatment), during (co-treatment) and after (post-treatment) treatment with the mutagens. Up to 100 μg/ml, β-caryophyllene by itself did not produce any cytotoxic and genotoxic effect, as shown by the value of the nuclear division index (NDI) and the frequency of micronuclei (MN). The test compound (0.1–100 μg/ml) significantly reduced the MN frequency induced by EMS in pre- and co-treatment protocols (up to 64.4% and 87% reduction, respectively). In the post-treatment protocol, β-caryophyllene was not effective as an antimutagen. No significant reduction of COL-induced MN frequency was found. The antigenotoxic activity of β-caryophyllene observed here suggests that this compound could act by chemical interaction with the mutagen in the growth medium (co-treatment) or in the cytoplasm of lymphocytes (pre-treatment), so acting as a desmutagen. These data encourage further studies to investigate the mode of action and the potential use of this compound as a chemopreventive agent.