The medicinal plant Scutellaria baicalensis Georgi has been used widely in traditional Chinese medicine for anti-inflammation, anticancer, antiviral and antibacterial infections, reducing the total cholesterol level and decreasing blood pressures. Baicalein and baicalin are two major flavonoid of Scutellaria baicalensis Georgi, exhibit various bioactivities. In the present study, the stimulatory activity of baicalin and baicalein derived from Scutellaria baicalensis on insulin secretion in vitro was investigated using HIT-T15 cell, a Syrian hamster transformed β-cell line. The survival rate of cells treated with baicalin or baicalein (0.01-0.5 mg/ml) increased significantly (P < 0.05). In the presence of 5.6 mM glucose, baicalin or baicalein (0.01-0.5 mg/ml) increased glucose-stimulated insulin secretion and cellular ATP levels in HIT-T15 cells. Baicalin and baicalein exhibited significant stimulatory activity in a dose-dependent manner without apparent cytotoxicity at concentrations less than 0.1 mg/ml. The results obtained in this study suggest that baicalin or baicalein increases the insulin secretion of HIT-T15 cells by the enhancement of β-cells activity and cellular ATP levels. Baicalin or baicalein could be candidates for a new class of anti-diabetic drugs.