OBJECTIVE:To investigate the potential chronic liver toxicity of oral administration of ethanol extract of Huangqin (Radix Scutellariae Baicalensis) (SBE) in Wistar rats.METHODS:SBE was administered to rats by gavage for 26 weeks,at doses of 300,1250,or 2500 mg · kg-1 · d-1 respectively.The rats were euthanized at the end of 13 and 26 weeks daily oral dosing and following 4 weeks of recovery time.The changes of hematology,urinary,blood biochemistry and histomorphology were examined at each time point and focus on liver function and histological changes.RESULTS:When SBE at a dose of up to 2500 mg ·kg-1 · d-1 was fed to male and female rats for 26 weeks,the liver tissue showed some inflammatory change that predominated by leukocyte infiltration but reted to normal after withdrawal.In addition,high-dose SBE treatment of 26 weeks in rats,glucose,electrolyte and lipid levels also have some changes.In addition,there are no other functional or organic lesions related to SBE treatment.CONCLUSIONS:Long-term and high-dose SBE may cause liver damage,however,the structural damage of the liver can be restored after the ethanol extract stopping.SBE will be well-tolerated for long-term use as a drug or health food,but in order to ensure drug safety,liver function,and serum glucose,electrolyte and lipid levels should be monitored when using SBE long term.