Farnesol in fruits, vegetables, herbs and leaves acts as bioactive component related with prevention of cancer and psychological malaise. We investigated the cytotoxic effects of farnesol on human leukemic cell, HL-60 cells, by MTT assay using 3- (4,5-Oirnethylthiazol-2-yl) -2,5-diphenyltetrazoliumbromide. Farnesol (0.1${sim}$50 ${mu}$g/ml) exhibited cytotoxicities against HL-60 cells in concentration and culture period dependent manner, In the cytotoxic condition induced by farnesol against HL-60 cells, the generation of reactive oxygen species such as O$_2$ and H$_2$O$_2$ were found to be considerably increased. The most prominent augmentations of O$_2$ and H$_2$O$_2$ were over five folds of controls. In an attempt to explore the response of HL-60 cells to the increased O$_2$ and H$_2$O$_2$, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase activities of HL-60 cells treated with farnesol were measured. SOD and GPx activities were found to be remarkably elevated by addition of farnesol showing the best results of 273% and 167% of controls, respectively: All data suggest that farnesol may have played as an apoptosis inducer in HL-60 cells via production of reactive oxygen species (ROS) and HL-60 cells may have failed to overcome the damage of ROS on account of still defcient ROS scavengers including SOD and GPx.