Abstract: The seasonal and source variations of flavonoid contents in Scutellariae Radix were investigated by using the materials collected at the same place in Liaoning Province, China, during three years, 1990-1992, and in seven other provinces in China. Four principal flavonoids in the plant roots, i.e., baicalin, baicalein, wogonin-7-O-glucuronide and wogonin were analyzed by using a reversed-phase chromatographic system with a chemically bonded ODS silica gel column and phosphate buffer-methanol (68:32 and 1:1) as mobile phase. The contents of the four compounds combined in the herb collected at Chengde, Hebei Province are the highest. The results show that the best time for harvesting the roots in Liaoning Province is the end of August.

Key words: Scutellariae Radix, Scutellaria baicalensis Georgi, Different sources, Different harvest times