Derivatives contained within rhubarb, demonstrated the hepatotoxic potential of emodin on normal rats and mice. The toxic effects included elevations of ALT levels, total bile acids levels and organ-weight-tobody-weight ratios of the liver, as well as decreases in alkaline phosphatase and total protein levels. Other investigators have reported that administration of rhubarb extracts led to elevations of serum ALT and TBIL levels in patients and experimental animals, leading to hepatitis and nephritis. The conflicting results of these reports might be due to the heterogeneity and complexity of herbal medicines with respect to their geographic origin, harvest season, and discrepancy of constituent components. Herbal medicines, which usually contain hundreds of chemical components with broad pharmacological targets and effects, present difficulties in KRX-0401 describing overall biological profiles in a simple manner with a few essential factors that can be readily comprehended. Many phytopharmacologists have dedicated themselves to solving this provlem for decades. In recent years, pattern recognition, a type of multivariate analysis approach, has become a promising method for identifying and interpreting meaningful regularities in noisy or complex systems, by analyzing data from different perspectives and summarizing them as useful information or by mining potential interrelationships. The factor analysis used in this study is a common pattern recognition method that reduces a large number of disease parameters to a relatively small number of independent factors, by describing the covariance structure of the observed data variables in terms of a few underlying and independent but nonmeasurable features called “factors”. The aim of this study was to determine the paradoxical effects of liver protection and hepatotoxicity of rhubarb in the treatment of rat experimental hepatitis induced by carbon tetrachloride by categorizing a number of functional bio-indices into separate complementary domains with no a priori assumptions. We believe that our data will provide useful information for the safe evaluation and proper application of rhubarb and, furthermore, will help increase our understanding of the rational use of phytomedicines. It has been previously reported that the protective effect of rhubarb against CCl4-induced liver lesions was largely attributed to the inhibition of the generation of free radicals and antioxidant activity. The mechanism of CCl4-induced liver injury is generally interpreted as follows: the compound is bioactivated by cytochrome P450 2E1 to the trichloromethyl free radical and then further converted to a peroxy radical, which leads to a chain reaction auto-oxidation of the fatty acids in the cytoplasmic membrane phospholipids causing functional and morphological changes to the cell membrane. As a consequence, the cell membranes of hepatocytes become more permeable, and enzymes such as ALT and AST can leak out into the bloodstream, leading to increased levels of these enzymes in the blood. These increases reflect the degree of hepatocyte damage and necrosis and vice versa.