Zerumbone (ZER) is a natural compound isolated from Zingiber zerumbet smith, family Zingiberaceae. It has been demonstrated to have an in vitro antiproliferative effects against various human tumour cells as well as in vivo against a number of induced malignancies in mice. The aim of our study was to assess the genotoxicity of ZER in CHO cells and using the bacterial mutagenicity Ames assay. The Methyl Thiazol Tetrazolium (MTT) screening assay was carried out to determine the cytotoxicity index (IC50) of ZER. The average IC50 value was 20.8 (±5.1) μM. Two cytogenetic end points were used to investigate the clastogenic effects of ZER, namely Chromosomal Aberrations (CA) assay and Micronucleus (MN) test. The micronucleus test and chromosome aberrations induction assay were performed without any metabolic activation. In the bacterial reverse mutagenicity assay (Ames test), there was no mutational change observed in Salmonella Typhimurium strain TA100 in the presence or absence of S-9 liver metabolic activation system. In contrast, MN induction and the frequency of chromosome aberrations in cultures treated with ZER increased significantly and dose-dependently. Chromatid and whole chromosome breaks/gaps, as well as dicentrics, interchanges, endoreduplications and ring chromosomes were the main types of aberrations induced by ZER. However, higher concentration was found to be toxic.