The cerebral vessels have sympathetic, parasympathetic, and sensory innervations. A sensory innervation of the cerebral vessels originating in the trigeminal ganglion has been described in a number of species by several investigations. It has been shown that the electrical stimulation of the trigeminal ganglion causes an increase of cerebral blood flow (CBF). The aim of our present study is to stimulate the trigeminal ganglion with an extracranial and non-invasive method. A stimulating electrode was put in the nasal mucosa via right nares of rabbits and trigeminal ganglion was stimulated orthodromically via nasociliary nerve (NCN). Variations in the cortical CBF were evaluated by laser Doppler flowmetry. In experiment group, CBF increased together with the beginning of electrical stimulation. The flow values were remained high as long as the stimulation. In post-stimulation period, the CBF was decreased gradually and returned to the baseline values at 120 s. This study demonstrated that the electrical stimulation of the NCN branch of the trigeminal nerve increases the cortical CBF under physiological conditions. (C) 2004 Elsevier Ireland Ltd. All rights reserved.