Objective: To investigate the effect of ginsenosides from stems and leaves of ginseng on ethanol-induced lipid deposition in human L02 hepatocytes. Methods: L02 cells were exposed to ethanol for 36 h and treated with or without ginsenosides. The viability of L02 cells was evaluated by methylthiazolyldiphenyl-tetrazolium bromide assay and the triglyceride (TG) content was detected. Lipid droplets were determined by oil red O staining. Intracellular reactive oxygen species (ROS) production and the mitochondrial membrane potential were tested by flow cytometry. The ATP level was measured by reverse phase high performance liquid chromatography. The expression of cytochrome p450 2E1 (CYP2E1) and peroxisome proliferator-activated receptor alpha (PPAR alpha) was detected by reverse transcriptase-polymerase chain reaction and Western blotting, respectively. Result: Ethanol exposure resulted in the increase of TG level, lipid accumulation and ROS generation, and the decrease of mitochondrial membrane potential and ATP production in the cells. However, ginsenosides significantly reduced TG content (9.69 +/- 0.22 mu g/mg protein vs. 4.93 +/- 0.49 mu g/mg protein, P < 0.01), and ROS formation (7254.8 +/- 385.7 vs. 5825.2 +/- 375.9, P < 0.01). Meanwhile, improvements in mitochondrial membrane potential (10655.33 +/- 331.34 vs. 11129.52 +/- 262.35, P < 0.05) and ATP level (1.20 +/- 0.18 nmol/mg protein vs. 2.53 +/- 0.25 nmol/mg protein, P < 0.01) were observed by treatment with ginsenosides. Furthermore, ginsenosides could down-regulate CYP2E1 expression (P < 0.01) and upregulate PPAR alpha expression (P < 0.01) in ethanol-treated cells. Conclusions: Ginsenosides could prevent ethanol-induced hepatocyte steatosis in vitro related to the inhibition of oxidative stress and the improvement of mitochondrial function. In addition, the modulation of CYP2E1 and PPAR alpha expression may also play an important role in the protective effect of ginsenosides against lipid accumulation.