Brain aromatase has been shown to be increased in expression after neurotoxic damage and to exert neuroprotection via generation of local oestrogens. The present study investigates the topography and time course of brain aromatase expression after experimental stroke (middle cerebral artery occlusion (MCAO)). Ovariectomised stroke prone spontaneously hypertensive rats underwent distal MCAO by electrocoagulation. Immunohistochemistry revealed increased brain aromatase expression at 24h and 8 days in the cortical penumbra/peri-infarct zones with no increase evident at 2h or 30 days post-MCAO. Double label studies indicate that some of the increased aromatase expression is associated with astrocytic processes. Thus, this is the first evidence that aromatase protein is increased after MCAO and the location (peri-infarct), time course (within 24h) and cellular localisation (astrocytic) indicate the potential for aromatase to promote the survival of cells in the penumbra after experimental stroke by local synthesis of oestrogens.