Silymarin is a complex mixture of four flavonolignan isomers (silybin, isosilybin, silydianin and silychristin) obtained from 'milk thistle' (Silybum marianum). This plant compound is used almost exclusively for hepatoprotection. Because of its low and poor oral bioavailability, silymarin was formulated as a nanoemulsion to increase its solubility (and so its oral bioavailability) as well as therapeutic activity. The present study assessed the hepatoprotective activity on Wistar rats by determining biochemical parameters and histopathological properties of the nanoemulsion formulation of silymarin against carbon tetrachloride (CCl(4))-induced hepatotoxicity. Hepatoprotective activity was evaluated by the activity of serum alkaline phosphatase, alanine transaminase and aspartate transaminase; antioxidative defence markers (concentration of reduced glutathione); oxidative stress parameter (thiobarbituric acid reactive substances) and liver histopathology. The nanoemulsion-treated group showed significant decreases in glutamate oxaloacetate transaminase, pyruvate transaminase, alkaline phosphotase, total bilirubin and tissue lipid peroxides and increased total protein, albumin, globulin and tissue glutathione as compared to toxicant. The results indicate an excellent potential of the nanoemulsion formulation for the reversal of CCl(4)-induced liver toxicity in rats as compared to standard silymarin.