Particle size fractionation by sieving is used to optimize antioxydant potential of natural substances. The aim of the present study was to evaluate particle size effects on antioxidant and hepatoprotective potential of Eucalyptus camaldulensis essential oils (EO) on CCl4-induced hepatic damage in Wistar rats. Animals were daily orally treated with the EOs extracted by hydrodistillation from powder sieved at four particle sizes (≥355, 200 - 355, 100 - 200, ≤100 μm) and those of the unsieved powder at dose of 50 mg/Kg for 7 days. Compounds that are evaluated for these activities are hydrocarbons and oxygenated terpenes that were identified and quantified by GC/MS. Activities of enzymes markers of hepatocellular damage in serum and antioxidant enzymes in the liver homogenates were measured. In this research, EOs significantly prevented the increase in serum ALT and AST (p < 0.05), total cholesterol, triglyceride and LDL-cholesterol level in acute liver damage induced by CCl4 and significant increase level of plasma HDL-cholesterol. Also, significantly (p < 0.05) decreased the extent of malondialdehyde (MDA) formation and elevated the activities of superoxide dismutase (SOD) and catalase (CAT) liver in comparison to negative control group. The best antioxidant and hepatoprotective activities were those of EOs from two fine powder fractions (≤100 μm and 100 - 200 μm) was correlated to their high concentration in oxygenated terpenes (70.9% and 46.4%, respectively), when compared to the large particles (200 - 355 μm and ≥355 μm, with 33.3% and 41.8%, respectively) and unsieved powder (37.4%).