Objective:To study antigenotoxic and apoptotic activities of hydrodistilled essential oil from the leaves of Atalantia monophylla Correa.Materials and Methods:Antigenotoxic activity of essential oil was tested against hydrogen peroxide (100 μM)-induced deoxyribonucleic acid (DNA) damage in 3T3-L1 cells. Cervical cancer cell (HeLa) growth inhibitory effect of essential oil was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay. Annexin V-fluorescein isothiocyanate/propidium iodide (FITC/PI), Hoechst 33258, and acridine orange/ethidium bromide (AO/EtBr) staining techniques were used to identify apoptosis.Results:DNA protecting the activity of A. monophylla essential oil was high at 125 μg/mL. HeLa cell growth was inhibited dose-dependently and inhibitory concentration 50% was calculated as 43.08 ± 0.02 μg/mL. Annexin V-FITC/PI double staining showed membrane breakage and nuclei staining. Further, Hoechst 33258 and AO/EtBr stain also confirmed the apoptosis in essential oil-treated HeLa cells.Conclusion:The results obtained suggest that A. monophylla essential oil is a promising natural agent which may be used in preparation of herbal medicine to treat cancer and other diseases.