AIM:To investigate the protective effect of extract of ginkgo biloba leaves(EGb)on the activity of retinal ganglion cells(RGC)in the continuous high intraocular pressure(IOP) SD rats.METHODS:Totally 20 healthy SD rats were established continuous high IOP models by cauterizing two episcleral vessels in the left eye. Then 12 rats satisfying experimental level(IOP>26mmHg) were selected and divided randomly into two groups, group A(control group) and group B(EGb treated group), 6 rats in each group. EGb was irrigated into the stomachs of rats in the treated group at the dose of 150mg/kg per day. The rat eyes were excised and made into eyeball samples after one month.The paraffin-embedded slides were stained with silver staining for nucleolar organizer region(AgNOR) to observe and count stained grains in RGC nucleus. RESULTS: Stained grains of RGC nucleus in model eye of group A was 1.33±0.07/cell,and group B was 1.83±0.09/cell, There was significant difference between group A and group B(P<0.05). Stained grains were more in group B than group A. Stained grains in RGC nucleus of the high IOP with EGb treated subgroup were more than those of the simple high IOP eyes. Stained grains were obviously decreased in the high IOP eye according to the normal IOP eye. Statistical significance was found between the high IOP eye and the normal IOP eye in the two groups (P<0.05) .CONCLUSION: Continuous high IOP in rats by cauterizing the episcleral vessels can result in the decrease of stained grains in RGC nucleus. EGb may have partial protective effect in RGC activity of high IOP rats.