['To study the effect of Ginkgo biloba extract (GBE) on the immune function of spleen and thymus in SD rats.', 'Forty SD rats were randomly divided into four groups (10 rats each group). Three experimental groups were given GBE daily by gavage in doses of 40, 120, 360 mg/(kg.d), respectively. Animals in the control group were fed the same amount of PBS. After 28 days, the rats were sacrificed by chloral hydrate anesthesia. The spleen and thymus were harvested to determine the organ index first. MTT assay was used to detect the concanavalin A (ConA)-induced splenic lymphocyte proliferation and transformation. Neutral red assay was performed to measure the rat peritoneal macrophage phagocytosis. The ultrastructural changes of spleen and thymus were observed under scanning electron microscope.', 'Administration of GBE in the rats increased the mass indexes of rat thymus and spleen, dose-dependently elevated the lymphocyte proliferative responses and enhanced the peritoneal macrophage phagocytosis. In experimental groups, the numbers of mature spleen and thymus lymphocytes were significantly raised in comparison with the control rats.'] Does [ Ginkgo biloba extract enhance the immune function of spleen and thymus in SD rats ]?