Abstract: Background and Objective: Zerumbone (ZER) is a sesquiterpene isolated from the rhizomes of Zingiber zerumbet smith, family Zingiberaceae. Anti-cancer and apoptosis-inducing properties of zerumbone against various human tumour cells have been elucidated earlier. The aim of this study was to further evaluate in vitro, the cytogenetic and DNA damage effects induced by ZER in Chinese Hamster Ovary (CHO) cells and in human peripheral blood lymphocytes. Methodology: Two cytogenetic end points were used to investigate the clastogenic effects of ZER, namely Chromosomal Aberrations (CA) assay in cultured human peripheral blood lymphocytes and micronucleus test (MN) in CHO cell lines. The alkaline single cell gel electrophoresis assay (comet assay) was used to evaluate the ability of ZER to induce DNA damage in stimulated cultured human Peripheral Blood Lymphocytes (PBL). The chromosome aberrations induction and comet assays were performed on human PBL without any metabolic activation. While S9 liver metabolic activation system was used in micronucleus test. Results: The obtained results showed that ZER has no significant effects on human peripheral blood lymphocyte chromosomes in all treatment concentrations, while the comet assay results showed that high concentrations can induce DNA damage, however the DNA damage was less pronounced than that caused by cisplatin. Conclusion: In addition, treatment with high concentrations was found to be genotoxic in MN induction in CHO cell cultures.