Abstract： Objective To observe the effects of scutellaria barbata extract (ESB) on proliferation, apoptosis and telomerase activity of human malignant glioma U251 cells in vitro.Methods Different concentrations of ESB (50, 25, 12.5, 6.25, 3.125 and 1.5625 mg/mL) were added into the medium cultured human malignant glioma U251 cells for 24, 48 and 72 h, respectively. And blank control group was also established. MTT assay was employed to detect the proliferation of U251cells. AnnexinV/PI staining and low cytometry (FCM) were used to detect the changes of apoptotic rate.And the telomerase activity of the cells was observed under the examination of telomeric repeat amplification protocol-PCR (TRAP-PCR)-ELISA.Results ESB inhibited the proliferation and induced the apoptosis of U251 cells. Interaction effect was found between the concentration of ESB and the treatment time of ESB by MTT assay (F=59.908, P=0.000); 50 mg/mL ESB for 72 h could most significantly inhibit the proliferation of U251 cells. Interaction effect was found between the concentration of ESB and the treatment time of ESB by AnnexinV/PI staining (F=6.548, P=0.000); 25mg/mL ESB for 72 h could most significantly induce the apoptosis of U251 cells. Interaction effect was also found between the concentration of ESB and the treatment time of ESB by TRAP-PCR-ELISA(F=138.433, P=0.000); the telomerase activity of the cells was the lowest by treatment with 50 mg/mL ESB for 72 h; negative correlation was noted between the telomerase activity of the cells and the apoptosis rate (r=-0.785, P=0.037); so as the telomerase activity of the cells and the inhibition effect (r=-0.278, P=0.042) Conclusion ESB may inhibit the proliferation and induces the apoptosis of U251 cells through down-regulating the telomerase activity.