Objective: To investigate the effects of Ginkgo leaf extract (GLE) on function of dendritic cells (DC) and Th1/Th2 cytokines in patients with unstable angina pectoris(UAP). Methods: Fifty-four patients with UAP were equally assigned into two groups, the treated group and the control group, both treated with conventional West medicine, but with GLE given additionally to the treated group. Blood of all patients was taken before and 4 weeks after treatment to prepare the peripheral mononuclear cells, then which were incubated in the completed medium containing granulocyte-macrophage colony stimulatory factor (GMCSF) and interleukin-4 (IL-4) to induce mature DC. The expression of co-stimulating factor CD86 (B7-2) on the surface of DC was detected by flow cytometry, and the stimulating capacity of DC was determined by mixed lymphocyte reaction (MLR). The blood levels of cytokines, interferon-γ (IFN-γ), and IL-4, were analyzed by ELISA, and blood C-reactive protein (CRP) level by turbidimetry. Moreover, the direct effect of Ginkgolide B on CD86 expression on DC were also tested in vitro. Results: After treatment, CD86 expression on DC, the stimulating capacity of DC as well as levels of IFN-γ and CRP were lowered in both groups ( P＜0.05 or P＜0.01), but the changes were much more significant in the treated group than those in the control group. Ginkgolide B showed a direct inhibitory effect on the CD86 expression on DC. Conclusion: The inhibition of GLE on DC and thereby the suppression on inflammatory reaction may be one of the mechanisms of GLE in treating patients with UAP.