In this study the effect of Centella asiatica L. extract was studied against genotoxic doses of ethinylestradiol on human lymphocytes culture. The different doses of C. asiatica L. extract i.e. 1.075x10-4, 2.125x10-4 and 3.15x10-4 g/ml were treated separately with 5 μM of ethinylestradiol. Similar treatments were given with 10 μM of ethinylestradiol. The treatments result in a significant dose dependent decrease in chromosomal aberrations and sister chromatid exchanges on human lymphocyte cultures induced by 5 and 10 μM of ethinylestradiol. The selected doses of C. asiatica L. extract were not genotoxic itself. Hence it is concluded that C. asiatica L. extract reduced the genotoxic damage during the ethinylestradiol therapy in patients and thereby reducing the chances of cancer development in humans.