Objective To investigate the different roles of metabolism of baicalein in rat,especial liver and intestine. Methods The enzyme re-actions by microsome incubations were employed. The content of baica-lein and baicalein- glucuronide were determined by HPLC. The glucu-ronidation rates of baicalein at different time points and at various con-centrations were measured by using 5 UGT microsomes. Results Five different microsomes are important common microsomes for glucuronida-tion of baicalein with the manner of time and concentration-dependences.Furthermore, the results also showed that jejunum microsome is the main microsome for metabolizing baicalein, and the colon microsome would be a weakest microsome for the contribution of baicalein metabolism. Con-clusion Different microsomes are responsible for the metabolism of ba-icalein in different organs/regions of the digestive system. The glucuroni-dation of baicalein in the intestine contributes significantly to that of ba-icalein in the liver.