Effects of betaine, a major component of Lycii Fructus, on carbon tetrachloride intoxicated rats were evaluated. Histological studies showed that betaine had improved the typical necrosis around centrilobular area in liver tissue due to the carbon tetrachloride intoxication. Betaine, whether it was administrated simultaneously or prior to carbon tetrachloride, prevented or retarded the elevation of liver-weight/body-weight ratio due to the carbon tetrachloride intoxication. Betaine also significantly elevated the reduced activities of some enzymes, cytochrome P-450, 7-ethoxycoumarin-0-deethylase and glutathione-S-transferase, involved in xenobiotic metabolism due to carbon tetrachloride intoxication. These results demonstrate a possible hepato-protective role of betaine against fatty liver that could be easily induced by carbon tetrachloride in rat.