OBJECTIVE To investigate the effect of baicalin complexion with phospholipids on the tissue distribution of rats and antihepatitis activity in mice.METHODS A new HPLC method was established to determine the concentrations of baicalin in tissues and plasma of rat.Antihepatitis activity was evaluated by the effect of baicalin-phospholipid complex on glutamic oxalacetic transaminase(GOT) and glutamic pyryvic transaminase(GPT) in mice.RESULTS The baicalin concentrations in stomach,kidney and plasma after oral intake of the complex were higher than those of the free drug.Significant differences were found between the complex and the free drug in kidney concentration at 12 h,in plasma concentrations at 5 and 8 h.Significant differences were also found between the complex and the physical mixture in plasma concentrations at 8 and 12 h after administration of drugs.The complex resulted in a more significant reduction in glutamic oxalacetic transaminase(GOT) and glutamic pyryvic transaminase(GPT),while the equivalent dose of baicalin induced only a significant reduction in GPT,and some decrease in these enzymes after oral intake of the physical mixture.The same efficacy was obtained with a half dose of the complex and a full dose of baicalin.CONCLUSION The results suggest that baicalin-phospholipid complex increased the absorption from the stomach and the concentrations in rat rich-blood tissues by improving the amphiphilicity of baicalin.It can be concluded that the complex enhance the absorption of free drug in vivo and exhibited more activity than baicalin.